Section Sound_Kripke.
Context {L: Language}
{minL: MinimumLanguage L}
{MD: Model}
{kMD: KripkeModel MD}
{M: Kmodel}
{R: Relation (Kworlds M)}
{po_R: PreOrder Krelation}
{SM: Semantics L MD}
{kiSM: KripkeIntuitionisticSemantics L MD M SM}
{kminSM: KripkeMinimumSemantics L MD M SM}.

Lemma sound_modus_ponens:
forall x y: expr,
forall m,
KRIPKE: M, m |= (x --> y) -> KRIPKE: M, m |= x -> KRIPKE: M, m |= y.