. rintro ⟨hp, hq⟩;
  by_contra hC;
  have : 𝓓 ⊢! [p, q].conj' ⟶ [p ⋏ q].disj' := by simp;
  have : 𝓓 ⊬! [p, q].conj' ⟶ [p ⋏ q].disj' := t.consistent (by aesop) (by simpa using t.not_mem₁_iff_mem₂.mp hC);
  contradiction;
case mpr
α : Type u_1
inst✝³ : DecidableEq α
inst✝² : Inhabited α
𝓓 : DeductionParameter α
inst✝¹ : 𝓓.IncludeEFQ
inst✝ : Encodable α
t✝ t t₁ t₂ : SCT 𝓓
p q : Formula α
⊢ p ∈ t.tableau.1 ∧ q ∈ t.tableau.1 → p ⋏ q ∈ t.tableau.1
no goals