intros.
unfold eqwordset in |- *.
intro w.
split.
unfold reconnait_A in |- *.
intro Ht; elim Ht; clear Ht.
intros H3 Ht; elim Ht; clear Ht.
intros e1 Ht; elim Ht; clear Ht.
intros e2 Ht; elim Ht; clear Ht.
intros H4 Ht; elim Ht; clear Ht.
intros H5 H6.
cut
(exists x1 : Elt,
(exists x2 : Elt,
(exists w1 : Word,
(exists w2 : Word,
dans x1 qa1 /\
dans x2 qd2 /\
chemin (first e1) x1 q1 d1 w1 /\
chemin x2 (first e2) q2 d2 w2 /\ w = Append w1 w2 :>Word)))).
2: apply par_le_pont with qd1 qa2; auto.
2: apply dans_map_trans with qd1; auto.
2: apply automate_def2 with qa1 d1; auto.
2: apply dans_map_trans with qa2; auto.
2: apply automate_def3 with qd2 d2; auto.
intros Ht; elim Ht; clear Ht.
intros x1 Ht; elim Ht; clear Ht.
intros x2 Ht; elim Ht; clear Ht.
intros w1 Ht; elim Ht; clear Ht.
intros w2 Ht; elim Ht; clear Ht.
intros H7 Ht; elim Ht; clear Ht.
intros H8 Ht; elim Ht; clear Ht.
intros H9 Ht; elim Ht; clear Ht.
intros H10 H11.
unfold lconc in |- *.
exists w1.
exists w2.
split.
unfold eqwordset in H0; elim (H0 w1).
intros.
apply H12.
unfold reconnait in |- *.
split.
apply Append_inmonoid_g with w2.
rewrite <- H11; auto.
exists (first e1).
exists x1.
split; auto.
apply dans_map_injg; auto.
split.
unfold eqwordset in H2; elim (H2 w2).
intros.
apply H12.
unfold reconnait in |- *.
split.
apply Append_inmonoid_d with w1.
rewrite <- H11; auto.
exists x2.
exists (first e2).
split; auto.
split; [ apply dans_map_injd; auto | auto ].
assumption.
unfold lconc in |- *.
intro Ht; elim Ht; clear Ht.
intros w1 Ht; elim Ht; clear Ht.
intros w2 Ht; elim Ht; clear Ht.
intros H3 Ht; elim Ht; clear Ht.
intros H4 H5.
cut (reconnait q1 qd1 qa1 d1 w1).
2: unfold eqwordset in H0.
2: elim (H0 w1); intros.
2: auto.
intro H6.
cut (reconnait q2 qd2 qa2 d2 w2).
2: unfold eqwordset in H2.
2: elim (H2 w2); intros.
2: auto.
intro H7.
rewrite H5.
elim H6.
intros H8 Ht; elim Ht; clear Ht; intros e1 Ht; elim Ht; clear Ht;
intros x1 Ht; elim Ht; clear Ht; intros H9 Ht; elim Ht;
clear Ht; intros H10 H11.
elim H7.
intros H12 Ht; elim Ht; clear Ht; intros x2 Ht; elim Ht; clear Ht;
intros e2 Ht; elim Ht; clear Ht; intros H13 Ht; elim Ht;
clear Ht; intros H14 H15.
unfold reconnait_A in |- *.
split.
apply inmonoid_Append; auto.
exists (couple e1 zero).
exists (couple e2 un).
split.
replace (couple e1 zero) with (injgauche e1); auto.
split.
replace (couple e2 un) with (injdroite e2); auto.
apply reconnait_Append with qd1 qa2 x1 x2; auto.
Qed.
(*  Si les langages l1 et l2 sont reguliers alors l1.l2 est aussi	*)
(*  regulier.								*)

Lemma lconc_is_reg :
forall l1 l2 : wordset,
isregular l1 -> isregular l2 -> isregular (lconc l1 l2).