intro
| inl ⟨hs, hu⟩ => constructor; left; exact hs; exact hu
| inr ⟨ht, hu⟩ => constructor; right; exact ht; exact hu
case a.mpr
α : Sort u_1
β : ?m.22335
γ : ?m.22338
s t u : Set α
x : α
⊢ x ∈ (s.inter u).union (t.inter u) → x ∈ (s.union t).inter u
no goals