Section DerivableRulesFromSequentCalculus.
Context {L: Language}
{Gamma: ProofTheory L}
{bSC: BasicSequentCalculus L Gamma}.
Context {minL: MinimunLanguage L}
{minSC: MinimunSequentCalculus L Gamma}.

Theorem deduction_theorem:
forall (Phi: context) (x y: expr),
Union _ Phi (Singleton _ x) |-- y <->
Phi |-- x --> y.