Definition meminj_no_overlap (f: meminj) (m: mem) : Prop :=
forall b1 b1' delta1 b2 b2' delta2 ofs1 ofs2,
b1 <> b2 ->
f b1 = Some (b1', delta1) ->
f b2 = Some (b2', delta2) ->
perm m b1 ofs1 Max Nonempty ->
perm m b2 ofs2 Max Nonempty ->
b1' <> b2' \/ ofs1 + delta1 <> ofs2 + delta2.

Lemma store_unmapped_inj:
forall f chunk m1 b1 ofs v1 n1 m2,
mem_inj f m1 m2 ->
store chunk m1 b1 ofs v1 = Some n1 ->
f b1 = None ->
mem_inj f n1 m2.