Definition join (j k:meminj):meminj := fun b =>
match j b with
Some (b1, delta) => Some (b1,delta)
| None => k b
end.
Definition disjoint (j k:meminj):Prop :=
forall b, j b = None \/ k b = None.

Lemma privChar: forall mu b1 b2 z, priv_of mu b1 = Some(b2,z) ->
pubBlocksSrc mu b1 = false.