simp
case nil
W : Type
M : KripkeModel W
w : W
N : ℕ
IH :
  ∀ m < [].length,
    ∀ (XS : List (List Formula)), XS.length = m → (evaluate M w (discon XS) ↔ ∃ Y ∈ XS, ∀ f ∈ Y, evaluate M w f)
⊢ evaluate M w (discon []) ↔ ∃ Y ∈ [], ∀ f ∈ Y, evaluate M w f
no goals