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

State before:
L : Language
L₁ : Language
L₂ : Language
L₃ : Language
ξ : Type u_1
ξ₁ : Type u_2
ξ₂ : Type u_3
ξ₃ : Type u_4
n n₁ n₂✝ n₂ m m₁ m₂ m₃ : ℕ
inst✝ : DecidableEq ξ
p q : Semiformula L ξ n
⊢ (p ⟶ q).fv = p.fv ∪ q.fv
Tactic:
simp [imp_eq]
State after:
no goals