proposition: Lemma inmon_Der_imp_inmon_R2_d : forall u v : Word, Regles X V2 R2 -> Derive R2 u v -> inmonoid (union X V2) u -> inmonoid (union X V2) v.
proof: Proof. prolog [ in_mon_X_Der_imp_inmon_X ] 10. Qed.
imports: Ensf Words more_words Rat need fonctions Relations gram gram2 gram3