Definition restrict_sm mu (X:block -> bool) :=
match mu with
Build_SM_Injection locBSrc locBTgt pSrc pTgt local extBSrc extBTgt fSrc fTgt extern =>
Build_SM_Injection locBSrc locBTgt pSrc pTgt (restrict local X)
extBSrc extBTgt fSrc fTgt (restrict extern X)
end.

Lemma restrict_sm_com: forall mu X Y,
restrict_sm (restrict_sm mu X) Y = restrict_sm (restrict_sm mu Y) X.