(*in extern_incr steps, sm_inject_separated_intern_MYB is not needed/trivial,
 since locBlocksSrc mu b = locBlocksSrc mu' b and locBlocksTgt mu b = locBlocksTgt mu' b*)

Definition sm_valid (mu : SM_Injection) (m1 m2: mem) :=
       (forall b1, DOM mu b1 -> Mem.valid_block m1 b1)
    /\ (forall b2, RNG mu b2 -> Mem.valid_block m2 b2).

Lemma intern_incr_refl: forall mu, intern_incr mu mu.