set A1 = Cl KurExSet;
set A2 = Cl (Int KurExSet);
set A3 = Cl (Int (Cl KurExSet));
thus Cl KurExSet <> Cl (Int KurExSet) by Th40; :: according to ZFMISC_1:def 5 :: thesis: ( not Cl KurExSet = Cl (Int (Cl KurExSet)) & not Cl (Int KurExSet) = Cl (Int (Cl KurExSet)) )
thus Cl KurExSet <> Cl (Int (Cl KurExSet)) by Th31; :: thesis: not Cl (Int KurExSet) = Cl (Int (Cl KurExSet))
thus not Cl (Int KurExSet) = Cl (Int (Cl KurExSet)) by Th33; :: thesis: verum