rintro ⟨wit⟩
case mpr
W : Type
ξ : Formula
M : KripkeModel W
δ : List Program
v : W
⊢ Nonempty (witness M v δ ξ) → (M, v)⊨(~⌈⌈δ⌉⌉ξ)
case mpr.intro
W : Type
ξ : Formula
M : KripkeModel W
δ : List Program
v : W
wit : witness M v δ ξ
⊢ (M, v)⊨(~⌈⌈δ⌉⌉ξ)