Definition mkinitial_SM (mu: SM_Injection) frgnS frgnT :=
  match mu with
  Build_SM_Injection locBSrc locBTgt pSrc pTgt local extBSrc extBTgt fSrc fTgt extern =>
  Build_SM_Injection (fun b => false) (fun b => false) (fun b => false) (fun b => false) (fun b => None)
                     (DomSrc mu) (DomTgt mu) frgnS frgnT (as_inj mu)
  end.

Lemma mkinitial_SM_equals_initial_SM: forall mu S T, mkinitial_SM mu S T = initial_SM (DomSrc mu) (DomTgt mu) S T (as_inj mu).