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(* as published by the Free Software Foundation; either version 2.1   *)
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(*                                                                    *)
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(* GNU General Public License for more details.                       *)
(*                                                                    *)
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(* 02110-1301 USA                                                     *)
(* conservation de l'invariant de compatibilité par rapport à une signature pour l'union *)

Lemma umerge_correct_wrt_sign_invar :
forall (d0 d1 : preDTA) (sigma : signature),
predta_correct_wrt_sign d0 sigma ->
predta_correct_wrt_sign d1 sigma ->
predta_correct_wrt_sign (u_merge d0 d1) sigma.