(*+ Hoare logic (single thread) *)
(** We now build a Hoare logic for a single thread based on the oracular semantics (it can assume that acquire will give back a good map, but has to provide back good maps at release.) *)
Definition safe_onethread G P c :=
forall m, m |= P -> forall oracle, safe step (G, oracle, m, c).
Definition semax G P c Q := forall F k,
safe_onethread G (Q ** F) k ->
safe_onethread G (P ** F) (c ++ k).

Lemma semax_post G P c (Q Q' : pred) :
imp Q Q' ->
semax G P c Q -> semax G P c Q'.