Definition removeUndefs (j l j':meminj):meminj :=
fun b => match j b with
None => match l b with
None => None | Some (b1,delta1) => j' b
end
| Some(b2,delta2) => Some(b2, delta2)
end.

Lemma RU_no_overlap:
forall m1 m2 j12 (MInj12 : Mem.inject j12 m1 m2) m1'
(Fwd1: mem_forward m1 m1') j23 m3
(MInj23 : Mem.inject j23 m2 m3) j' j12' j23' n1' n2'
(HeqMKI: mkInjections m1 m1' m2 j12 j23 j' = (j12',j23',n1',n2')),
Mem.meminj_no_overlap (removeUndefs j12 j' j12') m1'.