theorem Th15:
  QuantNbr(P!l) = QuantNbr(CQC_Sub([P!l,Sub]))
proof
  set S = [P!l,Sub];
  S = Sub_P(P,l,Sub) by SUBSTUT1:9;
  then
A1: CQC_Sub([(P!l),Sub]) = P!CQC_Subst(l,Sub) by SUBLEMMA:8;
  QuantNbr(P!CQC_Subst(l,Sub)) = 0 by CQC_SIM1:15;
  hence thesis by A1,CQC_SIM1:15;
end;
