(* Lemma unchanged_on_sym P m m' b: Mem.unchanged_on P m m' -> Mem.valid_block m b -> Mem.unchanged_on (fun bb z => P bb z /\ bb=b) m' m. *)

Lemma inject_separated_incr_fwd2:
forall j0 j j' m10 m20 m1 m2,
inject_incr j j' ->
inject_separated j j' m1 m2 ->
inject_incr j0 j ->
mem_forward m10 m1 ->
inject_separated j0 j m10 m20 ->
mem_forward m20 m2 ->
inject_separated j0 j' m10 m20.