simp only [fastAdmitsAux] at h1
case def_
v u : VarName
T : Finset VarName
a✝¹ : DefName
a✝ : List VarName
S : Finset VarName
h1 : fastAdmitsAux v u (S ∪ T) (def_ a✝¹ a✝)
⊢ fastAdmitsAux v u S (def_ a✝¹ a✝)
case def_
v u : VarName
T : Finset VarName
a✝¹ : DefName
a✝ : List VarName
S : Finset VarName
h1 : v ∈ a✝ → u ∉ S ∪ T
⊢ fastAdmitsAux v u S (def_ a✝¹ a✝)