(*TODO: Move to ev_semantics*)
Definition in_free_list (b : block) ofs xs :=
exists x, List.In x xs /\
let '(b', lo, hi) := x in
b = b' /\
(lo <= ofs < hi)%Z.
Fixpoint in_free_list_trace (b : block) ofs es :=
match es with
| event_semantics.Free l :: es =>
in_free_list b ofs l \/ in_free_list_trace b ofs es
| _ :: es =>
in_free_list_trace b ofs es
| [:: ] =>
False
end.

(** If (b, ofs) is in the list of freed addresses then the permission was Freeable and became None or it was not allocated*)
Lemma ev_elim_free_1:
forall m ev m' b ofs,
ev_elim m ev m' ->
in_free_list_trace b ofs ev ->
(permission_at m b ofs Cur = Some Freeable \/
~ Mem.valid_block m b) /\
permission_at m' b ofs Cur = None /\
Mem.valid_block m' b /\
exists e, List.In e ev /\
match e with
| event_semantics.Free _ => True
| _ => False
end.