set A = KurExSet ;
( 4 in Cl (Int KurExSet ) & Int KurExSet = ].4,5.[ \/ ].5,+infty .[ ) by Th20, Th26, TOPS_1:def 1, XXREAL_1:236;
hence Cl (Int KurExSet ) <> Int KurExSet by XXREAL_1:223; :: thesis: verum