Definition AccessMap_II_FUN (b2:block):
           Z -> perm_kind -> option permission :=
  if plt b2 (Mem.nextblock m2)
  then (fun ofs2 k =>
       match j23 b2 with
         None => PMap.get b2 m2.(Mem.mem_access) ofs2 k
       | Some (b3,d3) =>
         match source j12 m1 b2 ofs2 with
             Some(b1,ofs1) => PMap.get b1 m1'.(Mem.mem_access) ofs1 k
           | None => PMap.get b2 m2.(Mem.mem_access) ofs2 k
           end
        end)
  else (fun ofs2 k =>
           match source j12' m1' b2 ofs2 with
              Some(b1,ofs1) => PMap.get b1 m1'.(Mem.mem_access) ofs1 k
            | None => None
          end).

Lemma mkAccessMap_II_existsT: forall N (VB : (Mem.nextblock m2 <= N)%positive) (VBJ12': forall b1 b2 delta, j12' b1 = Some (b2,delta) -> (b2 < N)%positive), { M : PMap.t (Z -> perm_kind -> option permission) | fst M = (fun k ofs => None) /\ forall b, PMap.get b M = AccessMap_II_FUN b}.