Theorem: LRAT.DefaultFormula.clear_insert_inductive_case (LeanSAT/LRAT/Formula/RupAddResult.lean)

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
ih : f.clear_insert_induction_motive f_assignments_size units (↑idx) assignments
⊢ f.clear_insert_induction_motive f_assignments_size units (↑idx + 1) (clearUnit assignments units[idx])
Tactic:
rcases ih with ⟨hsize, ih⟩
State after:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
⊢ f.clear_insert_induction_motive f_assignments_size units (↑idx + 1) (clearUnit assignments units[idx])

State before:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
⊢ f.clear_insert_induction_motive f_assignments_size units (↑idx + 1) (clearUnit assignments units[idx])
Tactic:
have hsize' : Array.size (clearUnit assignments units[idx]) = n := by
  rw [← clearUnit_preserves_size assignments units[idx]] at hsize
  exact hsize
State after:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
hsize' : (clearUnit assignments units[idx]).size = n
⊢ f.clear_insert_induction_motive f_assignments_size units (↑idx + 1) (clearUnit assignments units[idx])

State before:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
hsize' : (clearUnit assignments units[idx]).size = n
⊢ f.clear_insert_induction_motive f_assignments_size units (↑idx + 1) (clearUnit assignments units[idx])
Tactic:
apply Exists.intro hsize'
State after:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
hsize' : (clearUnit assignments units[idx]).size = n
⊢ ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := (clearUnit assignments units[idx])[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx + 1 ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx + 1 ∧
            ↑j2 ≥ ↑idx + 1 ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
hsize' : (clearUnit assignments units[idx]).size = n
⊢ ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := (clearUnit assignments units[idx])[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx + 1 ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx + 1 ∧
            ↑j2 ≥ ↑idx + 1 ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
intro i
State after:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
specialize ih i
State after:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih :
  let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := assignments[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx ∧
          ↑j2 ≥ ↑idx ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih :
  let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := assignments[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx ∧
          ↑j2 ≥ ↑idx ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
simp only [Fin.getElem_fin, ne_eq, exists_and_left, exists_and_right] at ih
State after:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih :
  (assignments[↑i] = f.assignments[↑i] ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i) ∨
    (∃ j,
        ↑j ≥ ↑idx ∧
          ∃ x,
            (∃ x_1, units[↑j] = (⟨↑i, ⋯⟩, x)) ∧
              assignments[↑i] = addAssignment x f.assignments[↑i] ∧
                ¬hasAssignment x f.assignments[↑i] = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i) ∨
      ∃ j1,
        ↑j1 ≥ ↑idx ∧
          ∃ x,
            ↑x ≥ ↑idx ∧
              ∃ x_1,
                units[↑j1] = (⟨↑i, ⋯⟩, true) ∧
                  units[↑x] = (⟨↑i, ⋯⟩, false) ∧
                    assignments[↑i] = both ∧
                      f.assignments[↑i] = unassigned ∧
                        ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = x → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih :
  (assignments[↑i] = f.assignments[↑i] ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i) ∨
    (∃ j,
        ↑j ≥ ↑idx ∧
          ∃ x,
            (∃ x_1, units[↑j] = (⟨↑i, ⋯⟩, x)) ∧
              assignments[↑i] = addAssignment x f.assignments[↑i] ∧
                ¬hasAssignment x f.assignments[↑i] = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i) ∨
      ∃ j1,
        ↑j1 ≥ ↑idx ∧
          ∃ x,
            ↑x ≥ ↑idx ∧
              ∃ x_1,
                units[↑j1] = (⟨↑i, ⋯⟩, true) ∧
                  units[↑x] = (⟨↑i, ⋯⟩, false) ∧
                    assignments[↑i] = both ∧
                      f.assignments[↑i] = unassigned ∧
                        ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = x → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
rcases ih with
  ⟨ih1, ih2⟩ | ⟨j, j_ge_idx, ⟨b, ⟨i_gt_zero, ih1⟩, ih2, ih3, ih4⟩⟩ |
  ⟨j1, j1_ge_idx, j2, j2_ge_idx, i_gt_zero, ih1, ih2, ih3, ih4, ih5⟩
State after:
case intro.inl.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case intro.inr.inl.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case intro.inr.inr.intro.intro.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case intro.inl.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case intro.inr.inl.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case intro.inr.inr.intro.intro.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
. apply Or.inl
  constructor
  . simp only [clearUnit, Fin.getElem_fin, Array.get_eq_getElem]
    specialize ih2 idx (Nat.le_refl idx.val)
    have idx_unit_in_bounds : units[idx].1.1 < assignments.size := by
      rw [hsize]; exact units[idx].1.2.2
    have i_in_bounds : i.1 < assignments.size := by
      rw [hsize]
      exact i.2
    have h := Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds (removeAssignment units[idx.val].2) ih2
    simp only [Fin.getElem_fin] at h
    rw [h]
    exact ih1
  . intro j j_ge_idx_add_one
    exact ih2 j (Nat.le_of_succ_le j_ge_idx_add_one)
State after:
case intro.inr.inl.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case intro.inr.inr.intro.intro.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case intro.inr.inl.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case intro.inr.inr.intro.intro.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
. by_cases idx = j
  . next idx_eq_j =>
    apply Or.inl
    constructor
    . simp only [clearUnit, idx_eq_j, Array.get_eq_getElem, ih1]
      have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
      rw [Array.get_modify_at_idx i_in_bounds, ih2, remove_add_cancel]
      exact ih3
    . intro k k_ge_idx_add_one
      have k_ge_idx : k.val ≥ idx.val := Nat.le_of_succ_le k_ge_idx_add_one
      have k_ne_j : k ≠ j := by
        intro k_eq_j
        rw [k_eq_j, idx_eq_j] at k_ge_idx_add_one
        exact Nat.not_succ_le_self j.val k_ge_idx_add_one
      exact ih4 k k_ge_idx k_ne_j
  . next idx_ne_j =>
    refine Or.inr <| Or.inl <| ⟨j,b,i_gt_zero,?_⟩
    constructor
    . rw [← Nat.succ_eq_add_one]
      apply Nat.succ_le_of_lt ∘ Nat.lt_of_le_of_ne j_ge_idx
      intro idx_eq_j
      exact idx_ne_j (Fin.eq_of_val_eq idx_eq_j)
    . constructor
      . exact ih1
      . constructor
        . simp only [clearUnit, Array.get_eq_getElem]
          specialize ih4 idx (Nat.le_refl idx.1) idx_ne_j
          have idx_unit_in_bounds : units[idx.1].1.1 < assignments.size := by
            rw [hsize]
            exact units[idx.1].1.2.2
          have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
          rw [Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds _ ih4]
          exact ih2
        . constructor
          . exact ih3
          . intro k k_ge_idx_add_one k_ne_j
            exact ih4 k (Nat.le_of_succ_le k_ge_idx_add_one) k_ne_j
State after:
case intro.inr.inr.intro.intro.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case intro.inr.inr.intro.intro.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
. by_cases idx = j1
  . next idx_eq_j1 =>
    have idx_ne_j2 : idx ≠ j2 := by
      rw [idx_eq_j1]
      intro j1_eq_j2
      simp only [j1_eq_j2, ih2, Prod.mk.injEq, and_false] at ih1
    refine Or.inr <| Or.inl <| ⟨j2, false, i_gt_zero, ?_⟩
    constructor
    . apply Nat.le_of_lt_succ
      rw [← Nat.succ_eq_add_one]
      apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j2_ge_idx
      intro idx_eq_j2
      exact idx_ne_j2 (Fin.eq_of_val_eq idx_eq_j2)
    . constructor
      . simp only [Fin.getElem_fin]
        exact ih2
      . constructor
        . simp only [clearUnit, idx_eq_j1, Array.get_eq_getElem, ih1]
          have i_in_bounds : i.1 < assignments.size := hsize ▸ i.2
          rw [Array.get_modify_at_idx i_in_bounds, ih3, ih4]
          decide
        . constructor
          . simp only [hasAssignment, hasNegAssignment, ih4, ite_false, not_false_eq_true]
          . intro k k_ge_idx_add_one k_ne_j2
            intro h1
            by_cases units[k.1].2
            . next h2 =>
              have k_ne_j1 : k ≠ j1 := by
                rw [← idx_eq_j1]
                intro k_eq_idx
                rw [k_eq_idx] at k_ge_idx_add_one
                exact Nat.lt_irrefl idx.1 $ Nat.lt_of_succ_le k_ge_idx_add_one
              have h3 := units_nodup k j1 k_ne_j1
              simp only [Fin.getElem_fin, ih1, ← h1, ← h2, ne_eq] at h3
              exact h3 rfl
            . next h2 =>
              have h3 := units_nodup k j2 k_ne_j2
              simp only [Bool.not_eq_true] at h2
              simp only [Fin.getElem_fin, ih2, ← h1, ← h2, ne_eq] at h3
              exact h3 rfl
  . next idx_ne_j1 =>
    by_cases idx = j2
    . next idx_eq_j2 =>
      refine Or.inr <| Or.inl <| ⟨j1, true, i_gt_zero, ?_⟩
      constructor
      . apply Nat.le_of_lt_succ
        rw [← Nat.succ_eq_add_one]
        apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j1_ge_idx
        intro idx_eq_j1
        exact idx_ne_j1 (Fin.eq_of_val_eq idx_eq_j1)
      . constructor
        . simp only [Fin.getElem_fin]
          exact ih1
        . constructor
          . simp only [clearUnit, idx_eq_j2, Array.get_eq_getElem, ih2]
            have i_in_bounds : i.1 < assignments.size := hsize ▸ i.2
            rw [Array.get_modify_at_idx i_in_bounds, ih3, ih4]
            decide
          . constructor
            . simp only [hasAssignment, hasNegAssignment, ih4, ite_false, not_false_eq_true]
              decide
            . intro k k_ge_idx_add_one k_ne_j1
              intro h1
              by_cases units[k.1].2
              . next h2 =>
                have h3 := units_nodup k j1 k_ne_j1
                simp only [Fin.getElem_fin, ih1, ← h1, ← h2, ne_eq] at h3
                exact h3 rfl
              . next h2 =>
                have k_ne_j2 : k ≠ j2 := by
                  rw [← idx_eq_j2]
                  intro k_eq_idx
                  rw [k_eq_idx] at k_ge_idx_add_one
                  exact Nat.lt_irrefl idx.1 $ Nat.lt_of_succ_le k_ge_idx_add_one
                have h3 := units_nodup k j2 k_ne_j2
                simp only [Bool.not_eq_true] at h2
                simp only [Fin.getElem_fin, ih2, ← h1, ← h2, ne_eq] at h3
                exact h3 rfl
    . next idx_ne_j2 =>
      refine Or.inr <| Or.inr <| ⟨j1, j2,i_gt_zero, ?_⟩
      constructor
      . apply Nat.le_of_lt_succ
        rw [← Nat.succ_eq_add_one]
        apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j1_ge_idx
        intro idx_eq_j1
        exact idx_ne_j1 (Fin.eq_of_val_eq idx_eq_j1)
      . constructor
        . apply Nat.le_of_lt_succ
          rw [← Nat.succ_eq_add_one]
          apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j2_ge_idx
          intro idx_eq_j2
          exact idx_ne_j2 (Fin.eq_of_val_eq idx_eq_j2)
        . constructor
          . simp only [Fin.getElem_fin]
            exact ih1
          . constructor
            . simp only [Fin.getElem_fin]
              exact ih2
            . constructor
              . simp only [clearUnit, Array.get_eq_getElem]
                have idx_res_ne_i : units[idx.1].1.1 ≠ i.1 := by
                  intro h1
                  by_cases units[idx.1].2
                  . next h2 =>
                    have h3 := units_nodup idx j1 idx_ne_j1
                    simp only [Fin.getElem_fin, ih1, ← h1, ← h2, ne_eq] at h3
                    exact h3 rfl
                  . next h2 =>
                    have h3 := units_nodup idx j2 idx_ne_j2
                    simp only [Bool.not_eq_true] at h2
                    simp only [Fin.getElem_fin, ih2, ← h1, ← h2, ne_eq] at h3
                    exact h3 rfl
                have idx_unit_in_bounds : units[idx.1].1.1 < assignments.size := by
                  rw [hsize]; exact units[idx.1].1.2.2
                have i_in_bounds : i.1 < assignments.size := hsize ▸ i.2
                rw [Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds _ idx_res_ne_i]
                exact ih3
              . constructor
                . exact ih4
                . intro k k_ge_idx_add_one
                  exact ih5 k $ Nat.le_of_succ_le k_ge_idx_add_one
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
⊢ (clearUnit assignments units[idx]).size = n
Tactic:
rw [← clearUnit_preserves_size assignments units[idx]] at hsize
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize✝ : assignments.size = n
hsize : (clearUnit assignments units[idx]).size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
⊢ (clearUnit assignments units[idx]).size = n

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize✝ : assignments.size = n
hsize : (clearUnit assignments units[idx]).size = n
ih :
  ∀ (i : Fin n),
    let_fun i_lt_assignments_size := ⋯;
    let_fun i_lt_f_assignments_size := ⋯;
    let assignments_i := assignments[↑i];
    let fassignments_i := f.assignments[↑i];
    (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx → units[j].fst.val ≠ ↑i) ∨
      (∃ j b i_gt_zero,
          ↑j ≥ ↑idx ∧
            units[j] = (⟨↑i, ⋯⟩, b) ∧
              assignments_i = addAssignment b fassignments_i ∧
                ¬hasAssignment b fassignments_i = true ∧
                  ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j → units[k].fst.val ≠ ↑i) ∨
        ∃ j1 j2 i_gt_zero,
          ↑j1 ≥ ↑idx ∧
            ↑j2 ≥ ↑idx ∧
              units[j1] = (⟨↑i, ⋯⟩, true) ∧
                units[j2] = (⟨↑i, ⋯⟩, false) ∧
                  assignments_i = both ∧
                    fassignments_i = unassigned ∧
                      ∀ (k : Fin units.size), ↑k ≥ ↑idx → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
⊢ (clearUnit assignments units[idx]).size = n
Tactic:
exact hsize
State after:
no goals

State before:
case intro.inl.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
apply Or.inl
State after:
case intro.inl.intro.h
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i] ∧
    ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i

State before:
case intro.inl.intro.h
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i] ∧
    ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i
Tactic:
constructor
State after:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i]

case intro.inl.intro.h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i

State before:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i]

case intro.inl.intro.h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i
Tactic:
. simp only [clearUnit, Fin.getElem_fin, Array.get_eq_getElem]
  specialize ih2 idx (Nat.le_refl idx.val)
  have idx_unit_in_bounds : units[idx].1.1 < assignments.size := by
    rw [hsize]; exact units[idx].1.2.2
  have i_in_bounds : i.1 < assignments.size := by
    rw [hsize]
    exact i.2
  have h := Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds (removeAssignment units[idx.val].2) ih2
  simp only [Fin.getElem_fin] at h
  rw [h]
  exact ih1
State after:
case intro.inl.intro.h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i

State before:
case intro.inl.intro.h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i
Tactic:
. intro j j_ge_idx_add_one
  exact ih2 j (Nat.le_of_succ_le j_ge_idx_add_one)
State after:
no goals

State before:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i]
Tactic:
simp only [clearUnit, Fin.getElem_fin, Array.get_eq_getElem]
State after:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]

State before:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]
Tactic:
specialize ih2 idx (Nat.le_refl idx.val)
State after:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]

State before:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]
Tactic:
have idx_unit_in_bounds : units[idx].1.1 < assignments.size := by
  rw [hsize]; exact units[idx].1.2.2
State after:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]

State before:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]
Tactic:
have i_in_bounds : i.1 < assignments.size := by
  rw [hsize]
  exact i.2
State after:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]

State before:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]
Tactic:
have h := Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds (removeAssignment units[idx.val].2) ih2
State after:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
h : (assignments.modify units[idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = assignments[↑i]
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]

State before:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
h : (assignments.modify units[idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = assignments[↑i]
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]
Tactic:
simp only [Fin.getElem_fin] at h
State after:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
h : (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = assignments[↑i]
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]

State before:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
h : (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = assignments[↑i]
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = f.assignments[↑i]
Tactic:
rw [h]
State after:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
h : (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = assignments[↑i]
⊢ assignments[↑i] = f.assignments[↑i]

State before:
case intro.inl.intro.h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
h : (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = assignments[↑i]
⊢ assignments[↑i] = f.assignments[↑i]
Tactic:
exact ih1
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
⊢ units[idx].fst.val < assignments.size
Tactic:
rw [hsize]
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
⊢ units[idx].fst.val < n

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
⊢ units[idx].fst.val < n
Tactic:
exact units[idx].1.2.2
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
⊢ ↑i < assignments.size
Tactic:
rw [hsize]
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
⊢ ↑i < n

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[idx].fst.val < assignments.size
⊢ ↑i < n
Tactic:
exact i.2
State after:
no goals

State before:
case intro.inl.intro.h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i
Tactic:
intro j j_ge_idx_add_one
State after:
case intro.inl.intro.h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
j : Fin units.size
j_ge_idx_add_one : ↑j ≥ ↑idx + 1
⊢ units[j].fst.val ≠ ↑i

State before:
case intro.inl.intro.h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
ih1 : assignments[↑i] = f.assignments[↑i]
ih2 : ∀ (j : Fin units.size), ↑j ≥ ↑idx → ¬units[↑j].fst.val = ↑i
j : Fin units.size
j_ge_idx_add_one : ↑j ≥ ↑idx + 1
⊢ units[j].fst.val ≠ ↑i
Tactic:
exact ih2 j (Nat.le_of_succ_le j_ge_idx_add_one)
State after:
no goals

State before:
case intro.inr.inl.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
by_cases idx = j
State after:
case pos
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
h✝ : idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case neg
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
h✝ : ¬idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case pos
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
h✝ : idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case neg
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
h✝ : ¬idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
. next idx_eq_j =>
  apply Or.inl
  constructor
  . simp only [clearUnit, idx_eq_j, Array.get_eq_getElem, ih1]
    have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
    rw [Array.get_modify_at_idx i_in_bounds, ih2, remove_add_cancel]
    exact ih3
  . intro k k_ge_idx_add_one
    have k_ge_idx : k.val ≥ idx.val := Nat.le_of_succ_le k_ge_idx_add_one
    have k_ne_j : k ≠ j := by
      intro k_eq_j
      rw [k_eq_j, idx_eq_j] at k_ge_idx_add_one
      exact Nat.not_succ_le_self j.val k_ge_idx_add_one
    exact ih4 k k_ge_idx k_ne_j
State after:
case neg
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
h✝ : ¬idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case neg
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
h✝ : ¬idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
. next idx_ne_j =>
  refine Or.inr <| Or.inl <| ⟨j,b,i_gt_zero,?_⟩
  constructor
  . rw [← Nat.succ_eq_add_one]
    apply Nat.succ_le_of_lt ∘ Nat.lt_of_le_of_ne j_ge_idx
    intro idx_eq_j
    exact idx_ne_j (Fin.eq_of_val_eq idx_eq_j)
  . constructor
    . exact ih1
    . constructor
      . simp only [clearUnit, Array.get_eq_getElem]
        specialize ih4 idx (Nat.le_refl idx.1) idx_ne_j
        have idx_unit_in_bounds : units[idx.1].1.1 < assignments.size := by
          rw [hsize]
          exact units[idx.1].1.2.2
        have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
        rw [Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds _ ih4]
        exact ih2
      . constructor
        . exact ih3
        . intro k k_ge_idx_add_one k_ne_j
          exact ih4 k (Nat.le_of_succ_le k_ge_idx_add_one) k_ne_j
State after:
no goals

State before:
case pos
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
h✝ : idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
next idx_eq_j =>
apply Or.inl
constructor
. simp only [clearUnit, idx_eq_j, Array.get_eq_getElem, ih1]
  have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
  rw [Array.get_modify_at_idx i_in_bounds, ih2, remove_add_cancel]
  exact ih3
. intro k k_ge_idx_add_one
  have k_ge_idx : k.val ≥ idx.val := Nat.le_of_succ_le k_ge_idx_add_one
  have k_ne_j : k ≠ j := by
    intro k_eq_j
    rw [k_eq_j, idx_eq_j] at k_ge_idx_add_one
    exact Nat.not_succ_le_self j.val k_ge_idx_add_one
  exact ih4 k k_ge_idx k_ne_j
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
apply Or.inl
State after:
case h
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i] ∧
    ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i

State before:
case h
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i] ∧
    ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i
Tactic:
constructor
State after:
case h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i]

case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i

State before:
case h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i]

case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i
Tactic:
. simp only [clearUnit, idx_eq_j, Array.get_eq_getElem, ih1]
  have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
  rw [Array.get_modify_at_idx i_in_bounds, ih2, remove_add_cancel]
  exact ih3
State after:
case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i

State before:
case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i
Tactic:
. intro k k_ge_idx_add_one
  have k_ge_idx : k.val ≥ idx.val := Nat.le_of_succ_le k_ge_idx_add_one
  have k_ne_j : k ≠ j := by
    intro k_eq_j
    rw [k_eq_j, idx_eq_j] at k_ge_idx_add_one
    exact Nat.not_succ_le_self j.val k_ge_idx_add_one
  exact ih4 k k_ge_idx k_ne_j
State after:
no goals

State before:
case h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ (clearUnit assignments units[idx])[↑i] = f.assignments[↑i]
Tactic:
simp only [clearUnit, idx_eq_j, Array.get_eq_getElem, ih1]
State after:
case h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ (assignments.modify (↑i) (removeAssignment b))[↑i] = f.assignments[↑i]

State before:
case h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ (assignments.modify (↑i) (removeAssignment b))[↑i] = f.assignments[↑i]
Tactic:
have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
State after:
case h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
i_in_bounds : ↑i < assignments.size
⊢ (assignments.modify (↑i) (removeAssignment b))[↑i] = f.assignments[↑i]

State before:
case h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
i_in_bounds : ↑i < assignments.size
⊢ (assignments.modify (↑i) (removeAssignment b))[↑i] = f.assignments[↑i]
Tactic:
rw [Array.get_modify_at_idx i_in_bounds, ih2, remove_add_cancel]
State after:
case h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
i_in_bounds : ↑i < assignments.size
⊢ ¬hasAssignment b f.assignments[↑i] = true

State before:
case h.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
i_in_bounds : ↑i < assignments.size
⊢ ¬hasAssignment b f.assignments[↑i] = true
Tactic:
exact ih3
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ ↑i < assignments.size
Tactic:
rw [hsize]
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ ↑i < n

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ ↑i < n
Tactic:
exact i.2
State after:
no goals

State before:
case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
⊢ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i
Tactic:
intro k k_ge_idx_add_one
State after:
case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
⊢ units[k].fst.val ≠ ↑i

State before:
case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
⊢ units[k].fst.val ≠ ↑i
Tactic:
have k_ge_idx : k.val ≥ idx.val := Nat.le_of_succ_le k_ge_idx_add_one
State after:
case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
k_ge_idx : ↑k ≥ ↑idx
⊢ units[k].fst.val ≠ ↑i

State before:
case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
k_ge_idx : ↑k ≥ ↑idx
⊢ units[k].fst.val ≠ ↑i
Tactic:
have k_ne_j : k ≠ j := by
  intro k_eq_j
  rw [k_eq_j, idx_eq_j] at k_ge_idx_add_one
  exact Nat.not_succ_le_self j.val k_ge_idx_add_one
State after:
case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
k_ge_idx : ↑k ≥ ↑idx
k_ne_j : k ≠ j
⊢ units[k].fst.val ≠ ↑i

State before:
case h.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
k_ge_idx : ↑k ≥ ↑idx
k_ne_j : k ≠ j
⊢ units[k].fst.val ≠ ↑i
Tactic:
exact ih4 k k_ge_idx k_ne_j
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
k_ge_idx : ↑k ≥ ↑idx
⊢ k ≠ j
Tactic:
intro k_eq_j
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
k_ge_idx : ↑k ≥ ↑idx
k_eq_j : k = j
⊢ False

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
k_ge_idx : ↑k ≥ ↑idx
k_eq_j : k = j
⊢ False
Tactic:
rw [k_eq_j, idx_eq_j] at k_ge_idx_add_one
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑j ≥ ↑j + 1
k_ge_idx : ↑k ≥ ↑idx
k_eq_j : k = j
⊢ False

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_eq_j : idx = j
k : Fin units.size
k_ge_idx_add_one : ↑j ≥ ↑j + 1
k_ge_idx : ↑k ≥ ↑idx
k_eq_j : k = j
⊢ False
Tactic:
exact Nat.not_succ_le_self j.val k_ge_idx_add_one
State after:
no goals

State before:
case neg
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
h✝ : ¬idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
next idx_ne_j =>
refine Or.inr <| Or.inl <| ⟨j,b,i_gt_zero,?_⟩
constructor
. rw [← Nat.succ_eq_add_one]
  apply Nat.succ_le_of_lt ∘ Nat.lt_of_le_of_ne j_ge_idx
  intro idx_eq_j
  exact idx_ne_j (Fin.eq_of_val_eq idx_eq_j)
. constructor
  . exact ih1
  . constructor
    . simp only [clearUnit, Array.get_eq_getElem]
      specialize ih4 idx (Nat.le_refl idx.1) idx_ne_j
      have idx_unit_in_bounds : units[idx.1].1.1 < assignments.size := by
        rw [hsize]
        exact units[idx.1].1.2.2
      have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
      rw [Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds _ ih4]
      exact ih2
    . constructor
      . exact ih3
      . intro k k_ge_idx_add_one k_ne_j
        exact ih4 k (Nat.le_of_succ_le k_ge_idx_add_one) k_ne_j
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
refine Or.inr <| Or.inl <| ⟨j,b,i_gt_zero,?_⟩
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ↑j ≥ ↑idx + 1 ∧
    units[j] = (⟨↑i, ⋯⟩, b) ∧
      (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
        ¬hasAssignment b f.assignments[↑i] = true ∧
          ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ↑j ≥ ↑idx + 1 ∧
    units[j] = (⟨↑i, ⋯⟩, b) ∧
      (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
        ¬hasAssignment b f.assignments[↑i] = true ∧
          ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
constructor
State after:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ↑j ≥ ↑idx + 1

case right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ units[j] = (⟨↑i, ⋯⟩, b) ∧
    (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
      ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i

State before:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ↑j ≥ ↑idx + 1

case right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ units[j] = (⟨↑i, ⋯⟩, b) ∧
    (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
      ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
. rw [← Nat.succ_eq_add_one]
  apply Nat.succ_le_of_lt ∘ Nat.lt_of_le_of_ne j_ge_idx
  intro idx_eq_j
  exact idx_ne_j (Fin.eq_of_val_eq idx_eq_j)
State after:
case right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ units[j] = (⟨↑i, ⋯⟩, b) ∧
    (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
      ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i

State before:
case right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ units[j] = (⟨↑i, ⋯⟩, b) ∧
    (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
      ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
. constructor
  . exact ih1
  . constructor
    . simp only [clearUnit, Array.get_eq_getElem]
      specialize ih4 idx (Nat.le_refl idx.1) idx_ne_j
      have idx_unit_in_bounds : units[idx.1].1.1 < assignments.size := by
        rw [hsize]
        exact units[idx.1].1.2.2
      have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
      rw [Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds _ ih4]
      exact ih2
    . constructor
      . exact ih3
      . intro k k_ge_idx_add_one k_ne_j
        exact ih4 k (Nat.le_of_succ_le k_ge_idx_add_one) k_ne_j
State after:
no goals

State before:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ↑j ≥ ↑idx + 1
Tactic:
rw [← Nat.succ_eq_add_one]
State after:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ↑j ≥ (↑idx).succ

State before:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ↑j ≥ (↑idx).succ
Tactic:
apply Nat.succ_le_of_lt ∘ Nat.lt_of_le_of_ne j_ge_idx
State after:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬↑idx = ↑j

State before:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬↑idx = ↑j
Tactic:
intro idx_eq_j
State after:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
idx_eq_j : ↑idx = ↑j
⊢ False

State before:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
idx_eq_j : ↑idx = ↑j
⊢ False
Tactic:
exact idx_ne_j (Fin.eq_of_val_eq idx_eq_j)
State after:
no goals

State before:
case right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ units[j] = (⟨↑i, ⋯⟩, b) ∧
    (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
      ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
constructor
State after:
case right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ units[j] = (⟨↑i, ⋯⟩, b)

case right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
    ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i

State before:
case right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ units[j] = (⟨↑i, ⋯⟩, b)

case right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
    ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
. exact ih1
State after:
case right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
    ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i

State before:
case right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
    ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
. constructor
  . simp only [clearUnit, Array.get_eq_getElem]
    specialize ih4 idx (Nat.le_refl idx.1) idx_ne_j
    have idx_unit_in_bounds : units[idx.1].1.1 < assignments.size := by
      rw [hsize]
      exact units[idx.1].1.2.2
    have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
    rw [Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds _ ih4]
    exact ih2
  . constructor
    . exact ih3
    . intro k k_ge_idx_add_one k_ne_j
      exact ih4 k (Nat.le_of_succ_le k_ge_idx_add_one) k_ne_j
State after:
no goals

State before:
case right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ units[j] = (⟨↑i, ⋯⟩, b)
Tactic:
exact ih1
State after:
no goals

State before:
case right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i] ∧
    ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
constructor
State after:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i]

case right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i

State before:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i]

case right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
. simp only [clearUnit, Array.get_eq_getElem]
  specialize ih4 idx (Nat.le_refl idx.1) idx_ne_j
  have idx_unit_in_bounds : units[idx.1].1.1 < assignments.size := by
    rw [hsize]
    exact units[idx.1].1.2.2
  have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
  rw [Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds _ ih4]
  exact ih2
State after:
case right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i

State before:
case right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
. constructor
  . exact ih3
  . intro k k_ge_idx_add_one k_ne_j
    exact ih4 k (Nat.le_of_succ_le k_ge_idx_add_one) k_ne_j
State after:
no goals

State before:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (clearUnit assignments units[idx])[↑i] = addAssignment b f.assignments[↑i]
Tactic:
simp only [clearUnit, Array.get_eq_getElem]
State after:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = addAssignment b f.assignments[↑i]

State before:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = addAssignment b f.assignments[↑i]
Tactic:
specialize ih4 idx (Nat.le_refl idx.1) idx_ne_j
State after:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = addAssignment b f.assignments[↑i]

State before:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = addAssignment b f.assignments[↑i]
Tactic:
have idx_unit_in_bounds : units[idx.1].1.1 < assignments.size := by
  rw [hsize]
  exact units[idx.1].1.2.2
State after:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[↑idx].fst.val < assignments.size
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = addAssignment b f.assignments[↑i]

State before:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[↑idx].fst.val < assignments.size
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = addAssignment b f.assignments[↑i]
Tactic:
have i_in_bounds : i.1 < assignments.size := by rw [hsize]; exact i.2
State after:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[↑idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = addAssignment b f.assignments[↑i]

State before:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[↑idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
⊢ (assignments.modify units[↑idx].fst.val (removeAssignment units[↑idx].snd))[↑i] = addAssignment b f.assignments[↑i]
Tactic:
rw [Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds _ ih4]
State after:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[↑idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
⊢ assignments[↑i] = addAssignment b f.assignments[↑i]

State before:
case right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[↑idx].fst.val < assignments.size
i_in_bounds : ↑i < assignments.size
⊢ assignments[↑i] = addAssignment b f.assignments[↑i]
Tactic:
exact ih2
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
⊢ units[↑idx].fst.val < assignments.size
Tactic:
rw [hsize]
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
⊢ units[↑idx].fst.val < n

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
⊢ units[↑idx].fst.val < n
Tactic:
exact units[idx.1].1.2.2
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[↑idx].fst.val < assignments.size
⊢ ↑i < assignments.size
Tactic:
rw [hsize]
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[↑idx].fst.val < assignments.size
⊢ ↑i < n

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
idx_ne_j : ¬idx = j
ih4 : ¬units[↑idx].fst.val = ↑i
idx_unit_in_bounds : units[↑idx].fst.val < assignments.size
⊢ ↑i < n
Tactic:
exact i.2
State after:
no goals

State before:
case right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬hasAssignment b f.assignments[↑i] = true ∧ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
constructor
State after:
case right.right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬hasAssignment b f.assignments[↑i] = true

case right.right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i

State before:
case right.right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬hasAssignment b f.assignments[↑i] = true

case right.right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
. exact ih3
State after:
case right.right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i

State before:
case right.right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
. intro k k_ge_idx_add_one k_ne_j
  exact ih4 k (Nat.le_of_succ_le k_ge_idx_add_one) k_ne_j
State after:
no goals

State before:
case right.right.right.left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ¬hasAssignment b f.assignments[↑i] = true
Tactic:
exact ih3
State after:
no goals

State before:
case right.right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
⊢ ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i
Tactic:
intro k k_ge_idx_add_one k_ne_j
State after:
case right.right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
k_ne_j : k ≠ j
⊢ units[k].fst.val ≠ ↑i

State before:
case right.right.right.right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j : Fin units.size
j_ge_idx : ↑j ≥ ↑idx
b : Bool
i_gt_zero : ↑i > 0
ih1 : units[↑j] = (⟨↑i, ⋯⟩, b)
ih2 : assignments[↑i] = addAssignment b f.assignments[↑i]
ih3 : ¬hasAssignment b f.assignments[↑i] = true
ih4 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j → ¬units[↑k].fst.val = ↑i
idx_ne_j : ¬idx = j
k : Fin units.size
k_ge_idx_add_one : ↑k ≥ ↑idx + 1
k_ne_j : k ≠ j
⊢ units[k].fst.val ≠ ↑i
Tactic:
exact ih4 k (Nat.le_of_succ_le k_ge_idx_add_one) k_ne_j
State after:
no goals

State before:
case intro.inr.inr.intro.intro.intro.intro.intro.intro.intro.intro.intro
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
by_cases idx = j1
State after:
case pos
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
h✝ : idx = j1
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case neg
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
h✝ : ¬idx = j1
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case pos
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
h✝ : idx = j1
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

case neg
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
h✝ : ¬idx = j1
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
. next idx_eq_j1 =>
  have idx_ne_j2 : idx ≠ j2 := by
    rw [idx_eq_j1]
    intro j1_eq_j2
    simp only [j1_eq_j2, ih2, Prod.mk.injEq, and_false] at ih1
  refine Or.inr <| Or.inl <| ⟨j2, false, i_gt_zero, ?_⟩
  constructor
  . apply Nat.le_of_lt_succ
    rw [← Nat.succ_eq_add_one]
    apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j2_ge_idx
    intro idx_eq_j2
    exact idx_ne_j2 (Fin.eq_of_val_eq idx_eq_j2)
  . constructor
    . simp only [Fin.getElem_fin]
      exact ih2
    . constructor
      . simp only [clearUnit, idx_eq_j1, Array.get_eq_getElem, ih1]
        have i_in_bounds : i.1 < assignments.size := hsize ▸ i.2
        rw [Array.get_modify_at_idx i_in_bounds, ih3, ih4]
        decide
      . constructor
        . simp only [hasAssignment, hasNegAssignment, ih4, ite_false, not_false_eq_true]
        . intro k k_ge_idx_add_one k_ne_j2
          intro h1
          by_cases units[k.1].2
          . next h2 =>
            have k_ne_j1 : k ≠ j1 := by
              rw [← idx_eq_j1]
              intro k_eq_idx
              rw [k_eq_idx] at k_ge_idx_add_one
              exact Nat.lt_irrefl idx.1 $ Nat.lt_of_succ_le k_ge_idx_add_one
            have h3 := units_nodup k j1 k_ne_j1
            simp only [Fin.getElem_fin, ih1, ← h1, ← h2, ne_eq] at h3
            exact h3 rfl
          . next h2 =>
            have h3 := units_nodup k j2 k_ne_j2
            simp only [Bool.not_eq_true] at h2
            simp only [Fin.getElem_fin, ih2, ← h1, ← h2, ne_eq] at h3
            exact h3 rfl
State after:
case neg
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
h✝ : ¬idx = j1
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case neg
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
h✝ : ¬idx = j1
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
. next idx_ne_j1 =>
  by_cases idx = j2
  . next idx_eq_j2 =>
    refine Or.inr <| Or.inl <| ⟨j1, true, i_gt_zero, ?_⟩
    constructor
    . apply Nat.le_of_lt_succ
      rw [← Nat.succ_eq_add_one]
      apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j1_ge_idx
      intro idx_eq_j1
      exact idx_ne_j1 (Fin.eq_of_val_eq idx_eq_j1)
    . constructor
      . simp only [Fin.getElem_fin]
        exact ih1
      . constructor
        . simp only [clearUnit, idx_eq_j2, Array.get_eq_getElem, ih2]
          have i_in_bounds : i.1 < assignments.size := hsize ▸ i.2
          rw [Array.get_modify_at_idx i_in_bounds, ih3, ih4]
          decide
        . constructor
          . simp only [hasAssignment, hasNegAssignment, ih4, ite_false, not_false_eq_true]
            decide
          . intro k k_ge_idx_add_one k_ne_j1
            intro h1
            by_cases units[k.1].2
            . next h2 =>
              have h3 := units_nodup k j1 k_ne_j1
              simp only [Fin.getElem_fin, ih1, ← h1, ← h2, ne_eq] at h3
              exact h3 rfl
            . next h2 =>
              have k_ne_j2 : k ≠ j2 := by
                rw [← idx_eq_j2]
                intro k_eq_idx
                rw [k_eq_idx] at k_ge_idx_add_one
                exact Nat.lt_irrefl idx.1 $ Nat.lt_of_succ_le k_ge_idx_add_one
              have h3 := units_nodup k j2 k_ne_j2
              simp only [Bool.not_eq_true] at h2
              simp only [Fin.getElem_fin, ih2, ← h1, ← h2, ne_eq] at h3
              exact h3 rfl
  . next idx_ne_j2 =>
    refine Or.inr <| Or.inr <| ⟨j1, j2,i_gt_zero, ?_⟩
    constructor
    . apply Nat.le_of_lt_succ
      rw [← Nat.succ_eq_add_one]
      apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j1_ge_idx
      intro idx_eq_j1
      exact idx_ne_j1 (Fin.eq_of_val_eq idx_eq_j1)
    . constructor
      . apply Nat.le_of_lt_succ
        rw [← Nat.succ_eq_add_one]
        apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j2_ge_idx
        intro idx_eq_j2
        exact idx_ne_j2 (Fin.eq_of_val_eq idx_eq_j2)
      . constructor
        . simp only [Fin.getElem_fin]
          exact ih1
        . constructor
          . simp only [Fin.getElem_fin]
            exact ih2
          . constructor
            . simp only [clearUnit, Array.get_eq_getElem]
              have idx_res_ne_i : units[idx.1].1.1 ≠ i.1 := by
                intro h1
                by_cases units[idx.1].2
                . next h2 =>
                  have h3 := units_nodup idx j1 idx_ne_j1
                  simp only [Fin.getElem_fin, ih1, ← h1, ← h2, ne_eq] at h3
                  exact h3 rfl
                . next h2 =>
                  have h3 := units_nodup idx j2 idx_ne_j2
                  simp only [Bool.not_eq_true] at h2
                  simp only [Fin.getElem_fin, ih2, ← h1, ← h2, ne_eq] at h3
                  exact h3 rfl
              have idx_unit_in_bounds : units[idx.1].1.1 < assignments.size := by
                rw [hsize]; exact units[idx.1].1.2.2
              have i_in_bounds : i.1 < assignments.size := hsize ▸ i.2
              rw [Array.get_modify_unchanged idx_unit_in_bounds i_in_bounds _ idx_res_ne_i]
              exact ih3
            . constructor
              . exact ih4
              . intro k k_ge_idx_add_one
                exact ih5 k $ Nat.le_of_succ_le k_ge_idx_add_one
State after:
no goals

State before:
case pos
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
h✝ : idx = j1
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
next idx_eq_j1 =>
have idx_ne_j2 : idx ≠ j2 := by
  rw [idx_eq_j1]
  intro j1_eq_j2
  simp only [j1_eq_j2, ih2, Prod.mk.injEq, and_false] at ih1
refine Or.inr <| Or.inl <| ⟨j2, false, i_gt_zero, ?_⟩
constructor
. apply Nat.le_of_lt_succ
  rw [← Nat.succ_eq_add_one]
  apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j2_ge_idx
  intro idx_eq_j2
  exact idx_ne_j2 (Fin.eq_of_val_eq idx_eq_j2)
. constructor
  . simp only [Fin.getElem_fin]
    exact ih2
  . constructor
    . simp only [clearUnit, idx_eq_j1, Array.get_eq_getElem, ih1]
      have i_in_bounds : i.1 < assignments.size := hsize ▸ i.2
      rw [Array.get_modify_at_idx i_in_bounds, ih3, ih4]
      decide
    . constructor
      . simp only [hasAssignment, hasNegAssignment, ih4, ite_false, not_false_eq_true]
      . intro k k_ge_idx_add_one k_ne_j2
        intro h1
        by_cases units[k.1].2
        . next h2 =>
          have k_ne_j1 : k ≠ j1 := by
            rw [← idx_eq_j1]
            intro k_eq_idx
            rw [k_eq_idx] at k_ge_idx_add_one
            exact Nat.lt_irrefl idx.1 $ Nat.lt_of_succ_le k_ge_idx_add_one
          have h3 := units_nodup k j1 k_ne_j1
          simp only [Fin.getElem_fin, ih1, ← h1, ← h2, ne_eq] at h3
          exact h3 rfl
        . next h2 =>
          have h3 := units_nodup k j2 k_ne_j2
          simp only [Bool.not_eq_true] at h2
          simp only [Fin.getElem_fin, ih2, ← h1, ← h2, ne_eq] at h3
          exact h3 rfl
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
have idx_ne_j2 : idx ≠ j2 := by
  rw [idx_eq_j1]
  intro j1_eq_j2
  simp only [j1_eq_j2, ih2, Prod.mk.injEq, and_false] at ih1
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ let_fun i_lt_assignments_size := ⋯;
  let_fun i_lt_f_assignments_size := ⋯;
  let assignments_i := (clearUnit assignments units[idx])[↑i];
  let fassignments_i := f.assignments[↑i];
  (assignments_i = fassignments_i ∧ ∀ (j : Fin units.size), ↑j ≥ ↑idx + 1 → units[j].fst.val ≠ ↑i) ∨
    (∃ j b i_gt_zero,
        ↑j ≥ ↑idx + 1 ∧
          units[j] = (⟨↑i, ⋯⟩, b) ∧
            assignments_i = addAssignment b fassignments_i ∧
              ¬hasAssignment b fassignments_i = true ∧
                ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j → units[k].fst.val ≠ ↑i) ∨
      ∃ j1 j2 i_gt_zero,
        ↑j1 ≥ ↑idx + 1 ∧
          ↑j2 ≥ ↑idx + 1 ∧
            units[j1] = (⟨↑i, ⋯⟩, true) ∧
              units[j2] = (⟨↑i, ⋯⟩, false) ∧
                assignments_i = both ∧
                  fassignments_i = unassigned ∧
                    ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
refine Or.inr <| Or.inl <| ⟨j2, false, i_gt_zero, ?_⟩
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ ↑j2 ≥ ↑idx + 1 ∧
    units[j2] = (⟨↑i, ⋯⟩, false) ∧
      (clearUnit assignments units[idx])[↑i] = addAssignment false f.assignments[↑i] ∧
        ¬hasAssignment false f.assignments[↑i] = true ∧
          ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ ↑j2 ≥ ↑idx + 1 ∧
    units[j2] = (⟨↑i, ⋯⟩, false) ∧
      (clearUnit assignments units[idx])[↑i] = addAssignment false f.assignments[↑i] ∧
        ¬hasAssignment false f.assignments[↑i] = true ∧
          ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
constructor
State after:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ ↑j2 ≥ ↑idx + 1

case right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ units[j2] = (⟨↑i, ⋯⟩, false) ∧
    (clearUnit assignments units[idx])[↑i] = addAssignment false f.assignments[↑i] ∧
      ¬hasAssignment false f.assignments[↑i] = true ∧
        ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case left
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ ↑j2 ≥ ↑idx + 1

case right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ units[j2] = (⟨↑i, ⋯⟩, false) ∧
    (clearUnit assignments units[idx])[↑i] = addAssignment false f.assignments[↑i] ∧
      ¬hasAssignment false f.assignments[↑i] = true ∧
        ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
. apply Nat.le_of_lt_succ
  rw [← Nat.succ_eq_add_one]
  apply Nat.succ_lt_succ ∘ Nat.lt_of_le_of_ne j2_ge_idx
  intro idx_eq_j2
  exact idx_ne_j2 (Fin.eq_of_val_eq idx_eq_j2)
State after:
case right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ units[j2] = (⟨↑i, ⋯⟩, false) ∧
    (clearUnit assignments units[idx])[↑i] = addAssignment false f.assignments[↑i] ∧
      ¬hasAssignment false f.assignments[↑i] = true ∧
        ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j2 → units[k].fst.val ≠ ↑i

State before:
case right
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
idx_ne_j2 : idx ≠ j2
⊢ units[j2] = (⟨↑i, ⋯⟩, false) ∧
    (clearUnit assignments units[idx])[↑i] = addAssignment false f.assignments[↑i] ∧
      ¬hasAssignment false f.assignments[↑i] = true ∧
        ∀ (k : Fin units.size), ↑k ≥ ↑idx + 1 → k ≠ j2 → units[k].fst.val ≠ ↑i
Tactic:
. constructor
  . simp only [Fin.getElem_fin]
    exact ih2
  . constructor
    . simp only [clearUnit, idx_eq_j1, Array.get_eq_getElem, ih1]
      have i_in_bounds : i.1 < assignments.size := hsize ▸ i.2
      rw [Array.get_modify_at_idx i_in_bounds, ih3, ih4]
      decide
    . constructor
      . simp only [hasAssignment, hasNegAssignment, ih4, ite_false, not_false_eq_true]
      . intro k k_ge_idx_add_one k_ne_j2
        intro h1
        by_cases units[k.1].2
        . next h2 =>
          have k_ne_j1 : k ≠ j1 := by
            rw [← idx_eq_j1]
            intro k_eq_idx
            rw [k_eq_idx] at k_ge_idx_add_one
            exact Nat.lt_irrefl idx.1 $ Nat.lt_of_succ_le k_ge_idx_add_one
          have h3 := units_nodup k j1 k_ne_j1
          simp only [Fin.getElem_fin, ih1, ← h1, ← h2, ne_eq] at h3
          exact h3 rfl
        . next h2 =>
          have h3 := units_nodup k j2 k_ne_j2
          simp only [Bool.not_eq_true] at h2
          simp only [Fin.getElem_fin, ih2, ← h1, ← h2, ne_eq] at h3
          exact h3 rfl
State after:
no goals

State before:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
⊢ idx ≠ j2
Tactic:
rw [idx_eq_j1]
State after:
n : Nat
f : DefaultFormula n
f_assignments_size : f.assignments.size = n
units : Array (Literal (PosFin n))
units_nodup : ∀ (i j : Fin units.size), i ≠ j → units[i] ≠ units[j]
idx : Fin units.size
assignments : Array Assignment
hsize : assignments.size = n
hsize' : (clearUnit assignments units[idx]).size = n
i : Fin n
j1 : Fin units.size
j1_ge_idx : ↑j1 ≥ ↑idx
j2 : Fin units.size
j2_ge_idx : ↑j2 ≥ ↑idx
i_gt_zero : ↑i > 0
ih1 : units[↑j1] = (⟨↑i, ⋯⟩, true)
ih2 : units[↑j2] = (⟨↑i, ⋯⟩, false)
ih3 : assignments[↑i] = both
ih4 : f.assignments[↑i] = unassigned
ih5 : ∀ (k : Fin units.size), ↑k ≥ ↑idx → ¬k = j1 → ¬k = j2 → ¬units[↑k].fst.val = ↑i
idx_eq_j1 : idx = j1
⊢ j1 ≠ j2