Admitted. (*Maybe include mem_step in Events.extcall_properties.?*)

(* Specifications: *)
Lemma extcall_sem_mem_step: forall name sg g vargs m t vres m' (E:Events.external_functions_sem name sg g vargs m t vres m'),
mem_step m m'.
Lemma extcall_mem_step g: forall ef vargs m t vres m' (E:Events.external_call ef g vargs m t vres m'),
mem_step m m'.
Lemma CLC_corestep_mem:
forall (g : genv) c (m : mem) c'  (m' : mem),
semantics.corestep (cl_core_sem g) c m c' m' ->
semantics.mem_step m m'.