Definition rs_recv_trans := ReceiveTrans rs_step_coh.Definition server_recv_acquire_trans := rs_recv_trans acquire_tag server_msg_wf.Definition server_recv_release_trans := rs_recv_trans release_tag server_msg_wf.Definition client_send_safe (this n : nid)
           (d : dstatelet) (msg : seq nat) :=
  HClient this n /\
  exists (HC : HClient this n) (C : coh d), prec (getSt_client C (client_send_this_in HC)) n msg.

Lemma client_step_def this to d msg : client_send_safe this to d msg <-> exists b pf, @client_step this to d msg pf = Some b.