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(* as published by the Free Software Foundation; either version 2.1   *)
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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 union_0_correct_wrt_sign_invar :
forall (d : preDTA) (a0 a1 : ad) (s : state) (sigma : signature),
predta_correct_wrt_sign d sigma ->
union_0 d a0 a1 = Some s -> state_correct_wrt_sign s sigma.