all_goals
  simp only [occursIn]
  tauto
case not_
v : VarName
a✝ : Formula
a_ih✝ : isBoundIn v a✝ → occursIn v a✝
h1 : isBoundIn v a✝
⊢ occursIn v a✝.not_

case imp_
v : VarName
a✝¹ a✝ : Formula
a_ih✝¹ : isBoundIn v a✝¹ → occursIn v a✝¹
a_ih✝ : isBoundIn v a✝ → occursIn v a✝
h1 : isBoundIn v a✝¹ ∨ isBoundIn v a✝
⊢ occursIn v (a✝¹.imp_ a✝)

case and_
v : VarName
a✝¹ a✝ : Formula
a_ih✝¹ : isBoundIn v a✝¹ → occursIn v a✝¹
a_ih✝ : isBoundIn v a✝ → occursIn v a✝
h1 : isBoundIn v a✝¹ ∨ isBoundIn v a✝
⊢ occursIn v (a✝¹.and_ a✝)

case or_
v : VarName
a✝¹ a✝ : Formula
a_ih✝¹ : isBoundIn v a✝¹ → occursIn v a✝¹
a_ih✝ : isBoundIn v a✝ → occursIn v a✝
h1 : isBoundIn v a✝¹ ∨ isBoundIn v a✝
⊢ occursIn v (a✝¹.or_ a✝)

case iff_
v : VarName
a✝¹ a✝ : Formula
a_ih✝¹ : isBoundIn v a✝¹ → occursIn v a✝¹
a_ih✝ : isBoundIn v a✝ → occursIn v a✝
h1 : isBoundIn v a✝¹ ∨ isBoundIn v a✝
⊢ occursIn v (a✝¹.iff_ a✝)

case forall_
v a✝¹ : VarName
a✝ : Formula
a_ih✝ : isBoundIn v a✝ → occursIn v a✝
h1 : v = a✝¹ ∨ isBoundIn v a✝
⊢ occursIn v (forall_ a✝¹ a✝)

case exists_
v a✝¹ : VarName
a✝ : Formula
a_ih✝ : isBoundIn v a✝ → occursIn v a✝
h1 : v = a✝¹ ∨ isBoundIn v a✝
⊢ occursIn v (exists_ a✝¹ a✝)
no goals