unfold Sim, Rim, Gim3, Vim, Gim2, Xim, Gim, imageGram in |- *; simpl in |- *.
prolog [ isGram4 image_Regles isGram3 dans_map_inv isGram5 ] 7.
(*Intro is_Gram; Intro Mots ; Intro intersec . Apply isGram5. Assumption. Assumption. Apply dans_map_inv ; Apply isGram3 with X R1 ; Assumption. Apply image_Regles; Apply isGram4 with S1; Assumption.*)
Qed.

Lemma Id_image_X : Id (union X V1) f -> Xim = X :>Ensf.
unfold Xim, Gim, imageGram in |- *; simpl in |- *.