Theorem: LRAT.DefaultFormula.insertRatUnits_preserves_assignments_invariant
Proof state before:
n : Nat
f : DefaultFormula n
hf : f.ratUnits = #[] ∧ f.assignments_invariant
units : List (Literal (PosFin n))
h :
  let assignments := (f.insertRatUnits units).fst.assignments;
  let_fun hsize := ⋯;
  let ratUnits := (f.insertRatUnits units).fst.ratUnits;
  insertUnit_invariant f.assignments ⋯ ratUnits assignments hsize
hsize : (f.insertRatUnits units).fst.assignments.size = n
i : PosFin n
b : Bool
p : PosFin n → Bool
hp :
  ∀ (x : DefaultClause n),
    (some x ∈ (f.insertRatUnits units).fst.clauses.data ∨
        (∃ a,
            (a, false) ∈ (f.insertRatUnits units).fst.rupUnits.data ∧ unit (a, false) = x ∨
              (a, true) ∈ (f.insertRatUnits units).fst.rupUnits.data ∧ unit (a, true) = x) ∨
          ∃ a,
            (a, false) ∈ (f.insertRatUnits units).fst.ratUnits.data ∧ unit (a, false) = x ∨
              (a, true) ∈ (f.insertRatUnits units).fst.ratUnits.data ∧ unit (a, true) = x) →
      ∃ a, (a, false) ∈ Clause.toList x ∧ decide (p a = false) = true ∨ (a, true) ∈ Clause.toList x ∧ p a = true
pf : p ⊨ f
j : Fin (f.insertRatUnits units).fst.ratUnits.size
b' : Bool
hb : hasAssignment b (addAssignment b' f.assignments[↑⟨i.val, ⋯⟩]) = true
i_gt_zero : ↑⟨i.val, ⋯⟩ > 0
h1 : (f.insertRatUnits units).fst.ratUnits[j] = (⟨↑⟨i.val, ⋯⟩, ⋯⟩, b')
h2 : (f.insertRatUnits units).fst.assignments[↑⟨i.val, ⋯⟩] = addAssignment b' f.assignments[↑⟨i.val, ⋯⟩]
h3 : ¬hasAssignment b' f.assignments[↑⟨i.val, ⋯⟩] = true
h4 :
  ∀ (k : Fin (f.insertRatUnits units).fst.ratUnits.size),
    k ≠ j → (f.insertRatUnits units).fst.ratUnits[k].fst.val ≠ ↑⟨i.val, ⋯⟩
b_eq_b' : b = b'
j_unit : DefaultClause n := unit (f.insertRatUnits units).fst.ratUnits[j]
j_unit_def : j_unit = unit (f.insertRatUnits units).fst.ratUnits[j]
⊢ p ⊨ (i, b)
Tactic:
have j_unit_in_insertRatUnits_res :
  ∃ i : PosFin n,
    (i, false) ∈ (insertRatUnits f units).1.ratUnits.data ∧ unit (i, false) = j_unit ∨
    (i, true) ∈ (insertRatUnits f units).1.ratUnits.data ∧ unit (i, true) = j_unit := by
  apply Exists.intro i
  rw [j_unit_def, h1]
  by_cases hb' : b'
  . rw [hb']
    apply Or.inr
    constructor
    . have h1 : (insertRatUnits f units).fst.ratUnits[j] = (i, true) := by
        rw [hb'] at h1
        simp only [h1, Prod.mk.injEq, and_true]
        apply Subtype.ext
        rfl
      rw [← h1]
      apply Array.getElem_mem_data
    . rfl
  . simp only [Bool.not_eq_true] at hb'
    rw [hb']
    apply Or.inl
    constructor
    . have h1 : (insertRatUnits f units).fst.ratUnits[j] = (i, false) := by
        rw [hb'] at h1
        simp only [h1, Prod.mk.injEq, and_true]
        apply Subtype.ext
        rfl
      rw [← h1]
      apply Array.getElem_mem_data
    . rfl
Proof state after:
n : Nat
f : DefaultFormula n
hf : f.ratUnits = #[] ∧ f.assignments_invariant
units : List (Literal (PosFin n))
h :
  let assignments := (f.insertRatUnits units).fst.assignments;
  let_fun hsize := ⋯;
  let ratUnits := (f.insertRatUnits units).fst.ratUnits;
  insertUnit_invariant f.assignments ⋯ ratUnits assignments hsize
hsize : (f.insertRatUnits units).fst.assignments.size = n
i : PosFin n
b : Bool
p : PosFin n → Bool
hp :
  ∀ (x : DefaultClause n),
    (some x ∈ (f.insertRatUnits units).fst.clauses.data ∨
        (∃ a,
            (a, false) ∈ (f.insertRatUnits units).fst.rupUnits.data ∧ unit (a, false) = x ∨
              (a, true) ∈ (f.insertRatUnits units).fst.rupUnits.data ∧ unit (a, true) = x) ∨
          ∃ a,
            (a, false) ∈ (f.insertRatUnits units).fst.ratUnits.data ∧ unit (a, false) = x ∨
              (a, true) ∈ (f.insertRatUnits units).fst.ratUnits.data ∧ unit (a, true) = x) →
      ∃ a, (a, false) ∈ Clause.toList x ∧ decide (p a = false) = true ∨ (a, true) ∈ Clause.toList x ∧ p a = true
pf : p ⊨ f
j : Fin (f.insertRatUnits units).fst.ratUnits.size
b' : Bool
hb : hasAssignment b (addAssignment b' f.assignments[↑⟨i.val, ⋯⟩]) = true
i_gt_zero : ↑⟨i.val, ⋯⟩ > 0
h1 : (f.insertRatUnits units).fst.ratUnits[j] = (⟨↑⟨i.val, ⋯⟩, ⋯⟩, b')
h2 : (f.insertRatUnits units).fst.assignments[↑⟨i.val, ⋯⟩] = addAssignment b' f.assignments[↑⟨i.val, ⋯⟩]
h3 : ¬hasAssignment b' f.assignments[↑⟨i.val, ⋯⟩] = true
h4 :
  ∀ (k : Fin (f.insertRatUnits units).fst.ratUnits.size),
    k ≠ j → (f.insertRatUnits units).fst.ratUnits[k].fst.val ≠ ↑⟨i.val, ⋯⟩
b_eq_b' : b = b'
j_unit : DefaultClause n := unit (f.insertRatUnits units).fst.ratUnits[j]
j_unit_def : j_unit = unit (f.insertRatUnits units).fst.ratUnits[j]
j_unit_in_insertRatUnits_res :
  ∃ i,
    (i, false) ∈ (f.insertRatUnits units).fst.ratUnits.data ∧ unit (i, false) = j_unit ∨
      (i, true) ∈ (f.insertRatUnits units).fst.ratUnits.data ∧ unit (i, true) = j_unit
⊢ p ⊨ (i, b)