P Q : Prop
⊢ ¬(P ∧ Q) ∧ (P ∨ Q) ↔ (¬P ↔ Q)
P Q : Prop
⊢ IsCompl P Q ↔ ¬(P ↔ Q)
rw [_root_.isCompl_iff, Prop.disjoint_iff, Prop.codisjoint_iff, not_iff]
no goals
P Q : Prop
⊢ ¬(P ∧ Q) ∧ (P ∨ Q) ↔ (¬P ↔ Q)
by_cases P <;> by_cases Q <;> simp [*]