Definition canonical_eval: PropositionalLanguage.Var -> canonical_frame -> Prop :=
fun p a => proj1_sig a (PropositionalLanguage.varp p).
Definition kMD: KripkeModel TrivialSemantics.MD :=
Build_KripkeModel TrivialSemantics.MD
unit (fun _ => canonical_frame) (fun u a v => canonical_eval v a).
Definition canonical_Kmodel: @Kmodel TrivialSemantics.MD kMD := tt.
Definition rel: bijection (Kworlds canonical_Kmodel) (sig cP) := bijection_refl.

Lemma TRUTH:
forall x: expr, forall m Phi, rel m Phi ->
(KRIPKE: canonical_Kmodel, m |= x <-> proj1_sig Phi x).