intro
| Or.inl ⟨f,hf,h⟩ => cases h; exists f; constructor; assumption; exists a; constructor; left; rfl; rfl
| Or.inr ⟨f,hf,x,hx,h⟩ => cases h; exists f; constructor; assumption; exists x; constructor; right; assumption; rfl
case a.mpr
α : Sort u_1
β : Sort u_2
f : Set (α → β)
a : α
s : Set α
y : β
⊢ y ∈ (Set.map (fun f => f a) f).union (f.bind fun f => Set.map f s) → y ∈ f.bind fun f => Set.map f (s.insert a)
no goals