Corollary mem_obs_eq_domain_ren:
    forall f m m',
      mem_obs_eq f m m' ->
      domain_memren f m.

Lemma weak_mem_obs_eq_nextblock: forall f m m' (Hobs_eq: weak_mem_obs_eq f m m'), (Mem.nextblock m <= Mem.nextblock m')%positive.