Theorem: LO.FirstOrder.Semiformula.open_iff (Logic/FirstOrder/Basic/Syntax/Formula.lean)

State before:
L : Language
ξ : Type u_1
n n₁ n₂✝ n₂ m m₁ m₂ m₃ : ℕ
p q : Semiformula L ξ n
⊢ (p ⟷ q).Open ↔ p.Open ∧ q.Open
Tactic:
simp[Open]
State after:
no goals