Section DerivableRulesFromAxiomatization1.
Context {L: Language}
{minL: MinimumLanguage L}
{pL: PropositionalLanguage L}
{Gamma: Provable L}
{minAX: MinimumAxiomatization L Gamma}
{ipGamma: IntuitionisticPropositionalLogic L Gamma}.

Lemma solve_orp_impp: forall x y z: expr,
|-- x --> z -> |-- y --> z -> |-- x || y --> z.