Definition mkInjections (m1 m1' m2:mem) (j k l: meminj)
                     :  meminj * meminj * block * block :=
  if plt (Mem.nextblock m1) (Mem.nextblock m1')
  then mkInjectionsN (Pos.to_nat (Mem.nextblock m1') - Pos.to_nat(Mem.nextblock m1))
                (Mem.nextblock m1)
                (Mem.nextblock m2) j k l
  else (j,k,Mem.nextblock m1,Mem.nextblock m2).

Lemma mkInjections_3: forall m1 m1' m2 j k l j' k' n1' n2' (HI: mkInjections m1 m1' m2 j k l = (j',k',n1',n2')) b1 b2 ofs2, j' b1 = Some(b2,ofs2) -> (j b1 = Some (b2,ofs2)) \/ (b1 = Mem.nextblock m1 /\ b2 = Mem.nextblock m2 /\ ofs2 = 0) \/ (exists m, (b1 = Mem.nextblock m1 + m /\ b2=Mem.nextblock m2 + m)%positive /\ ofs2=0).