Section DEDUCTION_THEOREM.
End DEDUCTION_THEOREM.
#[local] Existing Instance V.vec_isSetoid.

Lemma for_MP (Gamma : ensemble (frm L)) (Gamma' : ensemble (frm L)) (p : frm L) (q : frm L)
(PROVE1 : Gamma \proves Imp_frm p q)
(PROVE2 : Gamma' \proves p)
: E.union Gamma Gamma' \proves q.