Theorem: Smt.Reconstruct.Builtin.cnfIteNeg1 (Smt/Reconstruct/Builtin/Lemmas.lean)

State before:
c a b : Prop
h : Decidable c
⊢ (if c then a else b) ∨ ¬c ∨ ¬a
Tactic:
apply orImplies
State after:
case a
c a b : Prop
h : Decidable c
⊢ (¬if c then a else b) → ¬c ∨ ¬a

State before:
case a
c a b : Prop
h : Decidable c
⊢ (¬if c then a else b) → ¬c ∨ ¬a
Tactic:
intro hnite
State after:
case a
c a b : Prop
h : Decidable c
hnite : ¬if c then a else b
⊢ ¬c ∨ ¬a

State before:
case a
c a b : Prop
h : Decidable c
hnite : ¬if c then a else b
⊢ ¬c ∨ ¬a
Tactic:
match h with
| isTrue _    => exact Or.inr hnite
| isFalse hnc => exact Or.inl hnc
State after:
no goals

State before:
c a b : Prop
h : Decidable c
h✝ : c
hnite : ¬if c then a else b
⊢ ¬c ∨ ¬a
Tactic:
exact Or.inr hnite
State after:
no goals

State before:
c a b : Prop
h : Decidable c
hnc : ¬c
hnite : ¬if c then a else b
⊢ ¬c ∨ ¬a
Tactic:
exact Or.inl hnc
State after:
no goals