Ltac coinductive_case CIH :=
    apply W_tl; simpl in *; auto;
    apply CIH; simpl in *; auto.

Lemma MsgLocked_held : forall s c, lb_step_execution lb_step_async s -> now (occurred (MsgLocked c)) s -> next (fun s => held (nwState (evt_a (hd s)) (Client c)) = true) s.