Definition inj_offset_aligned (delta: Z) (size: Z) : Prop :=
forall chunk, size_chunk chunk <= size -> (align_chunk chunk | delta).

Lemma free_left_inj:
forall f m1 m2 b lo hi m1',
mem_inj f m1 m2 ->
free m1 b lo hi = Some m1' ->
mem_inj f m1' m2.