Remark inval_after_outside:
forall i lo hi c, i < lo \/ i > hi -> (inval_after lo hi c)##i = c##i.
Remark inval_after_contents:
forall chunk av i lo hi c,
(inval_after lo hi c)##i = Some (ACval chunk av) ->
c##i = Some (ACval chunk av) /\ (i < lo \/ i > hi).
Remark inval_before_outside:
forall i hi lo c, i < lo \/ i >= hi -> (inval_before hi lo c)##i = c##i.
Remark inval_before_contents_1:
forall i chunk av lo hi c,
lo <= i < hi -> (inval_before hi lo c)##i = Some(ACval chunk av) ->
c##i = Some(ACval chunk av) /\ i + size_chunk chunk <= hi.

Lemma max_size_chunk: forall chunk, size_chunk chunk <= 8.
Remark inval_before_contents:
forall i c chunk' av' j,
(inval_before i (i - 7) c)##j = Some (ACval chunk' av') ->
c##j = Some (ACval chunk' av') /\ (j + size_chunk chunk' <= i \/ i <= j).