tauto
case h
W : Type
M : KripkeModel W
w : W
N : ℕ
X : List Formula
XS : List (List Formula)
IH : evaluate M w (discon XS) ↔ ∃ Y ∈ XS, ∀ f ∈ Y, evaluate M w f
lhs : ∀ f ∈ X, evaluate M w f
⊢ ∀ f ∈ X, evaluate M w f
no goals