intros ? ? mu ge b1 b2 d map1 map2.
rewrite map1 in map2; discriminate.
Qed.

(* Specifications: *)
Lemma gsep_domain_eq:
forall {F1 F2 V1 V2} mu mu' (ge1: Genv.t F1 V1) (ge2: Genv.t F2 V2),
globals_separate ge1 mu mu' ->
genvs_domain_eq ge1 ge2 ->
globals_separate ge2 mu mu'.