-- Mathlib/.lake/packages/lean4/src/lean/Std/Tactic/BVDecide/LRAT/Internal/Formula/RatAddSound.lean
theorem safe_insert_of_performRatCheck_fold_success {n : Nat} (f : DefaultFormula n)
    (f_readyForRatAdd : ReadyForRatAdd f) (c : DefaultClause n) (pivot : Literal (PosFin n))
    (rupHints : Array Nat) (ratHints : Array (Nat × Array Nat))
    (pivot_in_c : pivot ∈ Clause.toList c)
    (ratHintsExhaustive_eq_true : ratHintsExhaustive f pivot ratHints = true)
    (performRatCheck_fold_success :
      (Array.foldl
        (fun x ratHint => if x.2 = true then performRatCheck x.1 (Literal.negate pivot) ratHint else (x.1, false))
        ((performRupCheck (insertRupUnits f (negate c)).1 rupHints).1, true) ratHints 0 (Array.size ratHints)).2 = true) :
    Equisat (PosFin n) f (insert f c)

Proof state:
case mp
n : Nat
f : DefaultFormula n
f_readyForRatAdd : f.ReadyForRatAdd
c : DefaultClause n
pivot : Literal (PosFin n)
rupHints : Array Nat
ratHints : Array (Nat × Array Nat)
pivot_in_c : pivot ∈ Clause.toList c
ratHintsExhaustive_eq_true : f.ratHintsExhaustive pivot ratHints = true
performRatCheck_fold_success :
  (Array.foldl (fun x ratHint => if x.snd = true then x.fst.performRatCheck pivot.negate ratHint else (x.fst, false))
        (((f.insertRupUnits c.negate).fst.performRupCheck rupHints).fst, true) ratHints).snd =
    true
⊢ Unsatisfiable (PosFin n) f → Unsatisfiable (PosFin n) (f.insert c)

Tactic:
intro h p pfc

Result:
case mp
n : Nat
f : DefaultFormula n
f_readyForRatAdd : f.ReadyForRatAdd
c : DefaultClause n
pivot : Literal (PosFin n)
rupHints : Array Nat
ratHints : Array (Nat × Array Nat)
pivot_in_c : pivot ∈ Clause.toList c
ratHintsExhaustive_eq_true : f.ratHintsExhaustive pivot ratHints = true
performRatCheck_fold_success :
  (Array.foldl (fun x ratHint => if x.snd = true then x.fst.performRatCheck pivot.negate ratHint else (x.fst, false))
        (((f.insertRupUnits c.negate).fst.performRupCheck rupHints).fst, true) ratHints).snd =
    true
h : Unsatisfiable (PosFin n) f
p : PosFin n → Bool
pfc : p ⊨ f.insert c
⊢ False

Proof state:
n : Nat
f : DefaultFormula n
f_readyForRatAdd : f.ReadyForRatAdd
c : DefaultClause n
pivot : Literal (PosFin n)
rupHints : Array Nat
ratHints : Array (Nat × Array Nat)
pivot_in_c : pivot ∈ Clause.toList c
ratHintsExhaustive_eq_true : f.ratHintsExhaustive pivot ratHints = true
performRatCheck_fold_success :
  (Array.foldl (fun x ratHint => if x.snd = true then x.fst.performRatCheck pivot.negate ratHint else (x.fst, false))
        (((f.insertRupUnits c.negate).fst.performRupCheck rupHints).fst, true) ratHints).snd =
    true
⊢ Equisat (PosFin n) f (f.insert c)

Tactic:
constructor

Result:
case mp
n : Nat
f : DefaultFormula n
f_readyForRatAdd : f.ReadyForRatAdd
c : DefaultClause n
pivot : Literal (PosFin n)
rupHints : Array Nat
ratHints : Array (Nat × Array Nat)
pivot_in_c : pivot ∈ Clause.toList c
ratHintsExhaustive_eq_true : f.ratHintsExhaustive pivot ratHints = true
performRatCheck_fold_success :
  (Array.foldl (fun x ratHint => if x.snd = true then x.fst.performRatCheck pivot.negate ratHint else (x.fst, false))
        (((f.insertRupUnits c.negate).fst.performRupCheck rupHints).fst, true) ratHints).snd =
    true
⊢ Unsatisfiable (PosFin n) f → Unsatisfiable (PosFin n) (f.insert c)

case mpr
n : Nat
f : DefaultFormula n
f_readyForRatAdd : f.ReadyForRatAdd
c : DefaultClause n
pivot : Literal (PosFin n)
rupHints : Array Nat
ratHints : Array (Nat × Array Nat)
pivot_in_c : pivot ∈ Clause.toList c
ratHintsExhaustive_eq_true : f.ratHintsExhaustive pivot ratHints = true
performRatCheck_fold_success :
  (Array.foldl (fun x ratHint => if x.snd = true then x.fst.performRatCheck pivot.negate ratHint else (x.fst, false))
        (((f.insertRupUnits c.negate).fst.performRupCheck rupHints).fst, true) ratHints).snd =
    true
⊢ Unsatisfiable (PosFin n) (f.insert c) → Unsatisfiable (PosFin n) f

Proof state:
case neg
n : Nat
f : DefaultFormula n
f_readyForRatAdd : f.ReadyForRatAdd
c : DefaultClause n
pivot : Literal (PosFin n)
rupHints : Array Nat
ratHints : Array (Nat × Array Nat)
pivot_in_c : Limplies (PosFin n) pivot c
ratHintsExhaustive_eq_true : f.ratHintsExhaustive pivot ratHints = true
performRatCheck_fold_success :
  (Array.foldl (fun x ratHint => if x.snd = true then x.fst.performRatCheck pivot.negate ratHint else (x.fst, false))
        (((f.insertRupUnits c.negate).fst.performRupCheck rupHints).fst, true) ratHints).snd =
    true
fc_unsat : Unsatisfiable (PosFin n) (f.insert c)
p : PosFin n → Bool
pf : p ⊨ f
pc : ¬(p ⊨ c)
p' : PosFin n → Bool := fun a => if a = pivot.fst then pivot.snd else p a
p'_entails_c : p' ⊨ c
⊢ False

Tactic:
specialize fc_unsat p'

Result:
case neg
n : Nat
f : DefaultFormula n
f_readyForRatAdd : f.ReadyForRatAdd
c : DefaultClause n
pivot : Literal (PosFin n)
rupHints : Array Nat
ratHints : Array (Nat × Array Nat)
pivot_in_c : Limplies (PosFin n) pivot c
ratHintsExhaustive_eq_true : f.ratHintsExhaustive pivot ratHints = true
performRatCheck_fold_success :
  (Array.foldl (fun x ratHint => if x.snd = true then x.fst.performRatCheck pivot.negate ratHint else (x.fst, false))
        (((f.insertRupUnits c.negate).fst.performRupCheck rupHints).fst, true) ratHints).snd =
    true
p : PosFin n → Bool
pf : p ⊨ f
pc : ¬(p ⊨ c)
p' : PosFin n → Bool := fun a => if a = pivot.fst then pivot.snd else p a
p'_entails_c : p' ⊨ c
fc_unsat : ¬(p' ⊨ f.insert c)
⊢ False