Notation coh := TPCCoh.Definition cn_safe (this n : nid)
           (d : dstatelet) (msg : data) :=
  HCn this n /\
  exists (C : coh d), prec (getStC C) n msg.

(* Specifications: *)
Lemma cn_safe_coh this to d m : cn_safe this to d m -> coh d.