let X, Y be non empty compact Subset of (TOP-REAL 2); :: thesis: ( E-bound X < E-bound Y implies E-min (X \/ Y) = E-min Y )
A1: (E-min (X \/ Y)) `1 = E-bound (X \/ Y) by EUCLID:52;
A2: X \/ Y is compact by COMPTS_1:10;
then A3: E-min (X \/ Y) in X \/ Y by SPRECT_1:14;
A4: E-min Y in Y by SPRECT_1:14;
A5: (E-min Y) `1 = E-bound Y by EUCLID:52;
assume A6: E-bound X < E-bound Y ; :: thesis: E-min (X \/ Y) = E-min Y
then A7: E-bound (X \/ Y) = E-bound Y by Th24;
Y c= X \/ Y by XBOOLE_1:7;
then E-min Y in E-most (X \/ Y) by A2, A7, A5, A4, SPRECT_2:13;
then A8: (E-min (X \/ Y)) `2 <= (E-min Y) `2 by A2, PSCOMP_1:47;
per cases ( E-min (X \/ Y) in Y or E-min (X \/ Y) in X ) by A3, XBOOLE_0:def 3;
suppose E-min (X \/ Y) in Y ; :: thesis: E-min (X \/ Y) = E-min Y
end;
suppose E-min (X \/ Y) in X ; :: thesis: E-min (X \/ Y) = E-min Y
hence E-min (X \/ Y) = E-min Y by A6, A7, A1, PSCOMP_1:24; :: thesis: verum
end;
end;