Definition perm_order''_dec : forall (op op' : option permission),
      {Mem.perm_order'' op op'} + {~ Mem.perm_order'' op op'}.Definition perm_eq_dec: forall (op op' : option permission),
      {op = op'} + {~ op = op'}.

(* Specifications: *)
Lemma storebytes_decay: forall m loc p vl m', Mem.storebytes m loc p vl = Some m' -> decay m m'.
Lemma alloc_decay: forall m lo hi m1 b1, Mem.alloc m lo hi = (m1,b1) -> decay m m1.
Lemma free_decay: forall m b lo hi m', Mem.free m b lo hi = Some m' -> decay m m'.
Lemma msem_decay: forall C (Sem: MemSem C) c m c' m', corestep (csem Sem) c m c' m' -> decay m m'.