(** or it wasn't and the operation denoted by the event implies the permission*)
(** *** Properties about permission decay and events *)

Lemma lockRes_freelock_step:
forall U tr tp m U' tp' m' tr' laddr rmap
(Hres: lockRes tp laddr = Some rmap)
(Hres': lockRes tp' laddr = None)
(Hstep: MachStep (U, tr, tp) m (U', tr ++ tr', tp') m'),
exists ev,
tr' = [:: ev] /\ action ev = Freelock /\
location ev = Some (laddr, lksize.LKSIZE_nat) /\
forall b ofs, rmap.1 !! b ofs = None /\ rmap.2 !! b ofs = None.