cases h with
| inl h =>
  apply membership_iff.mpr;
  exact efq_of_neg! $ membership_iff.mp $ iff_mem_neg.mpr h;
| inr h =>
  apply membership_iff.mpr;
  exact imply₁! ⨀ (membership_iff.mp h)
case mpr
α : Type u_1
inst✝² : DecidableEq α
inst✝¹ : Inhabited α
L : DeductionParameter α
inst✝ : L.Normal
Ω Ω₁ Ω₂ : MCT L
p q : Formula α
h : p ∉ Ω.theory ∨ q ∈ Ω.theory
⊢ p ⟶ q ∈ Ω.theory
no goals