Section DerivableRulesFromSequentCalculus.
Context {L: Language}
{GammaD: Derivable L}
{bSC: BasicSequentCalculus L GammaD}.
Context {minL: MinimumLanguage L}
{minSC: MinimumSequentCalculus L GammaD}.

Lemma deduction_impp_elim: forall Phi x y,
Phi |-- impp x y ->
Union _ Phi (Singleton _ x) |-- y.