Section ClassicalderivedRules.
Context {L: Language}
{minL: MinimumLanguage L}
{pL: PropositionalLanguage L}
{mL: ModalLanguage L}
{Gamma: Provable L}
{minAX: MinimumAxiomatization L Gamma}
{ipAX: IntuitionisticPropositionalLogic L Gamma}
{cpAX: ClassicalPropositionalLogic L Gamma}
{KmAX: SystemK L Gamma}.
Existing Instances Classical2GodelDummett GodelDummett2DeMorgan.

Lemma diamondp_orp: forall x y, |-- diamondp (x || y) <--> (diamondp x || diamondp y).