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

Lemma lockRes_lock_permission_decrease_step:
forall U tr tp m U' tp' m' tr' laddr rmap rmap' b ofs
(Hres: lockRes tp laddr = Some rmap)
(Hres': lockRes tp' laddr = Some rmap')
(Hstep: MachStep (U, tr, tp) m (U', tr ++ tr', tp') m')
(Hperm: Mem.perm_order'' (rmap.2 !! b ofs) (Some Readable))
(Hperm': ~ Mem.perm_order'' (rmap'.2 !! b ofs) (Some Readable)),
exists ev,
tr' = [:: ev] /\ action ev = Acquire /\
location ev = Some (laddr, lksize.LKSIZE_nat).