Section ToTarski.
Context {Σ_funcs : funcs_signature}.
Context {Σ_preds : preds_signature}.
Program Instance interp_kripke {domain} (I : interp domain) : kmodel domain :=
{| nodes := unit ; reachable u v := True |}.
Next Obligation.
- now apply I in X.
Defined.

Lemma kvalid_valid b (phi : form b) :
kvalid phi -> valid phi.