let r1, r2 be Real; :: thesis: ( ( for e being Real st e > 0 holds
ex Y0 being finite Subset of X st
( not Y0 is empty & Y0 c= Y & ( for Y1 being finite Subset of X st Y0 c= Y1 & Y1 c= Y holds
|.(r1 - (setopfunc (Y1, the carrier of X,REAL,L,addreal))).| < e ) ) ) & ( for e being Real st e > 0 holds
ex Y0 being finite Subset of X st
( not Y0 is empty & Y0 c= Y & ( for Y1 being finite Subset of X st Y0 c= Y1 & Y1 c= Y holds
|.(r2 - (setopfunc (Y1, the carrier of X,REAL,L,addreal))).| < e ) ) ) implies r1 = r2 )
assume that
A2: for e1 being Real st e1 > 0 holds
ex Y0 being finite Subset of X st
( not Y0 is empty & Y0 c= Y & ( for Y1 being finite Subset of X st Y0 c= Y1 & Y1 c= Y holds
|.(r1 - (setopfunc (Y1, the carrier of X,REAL,L,addreal))).| < e1 ) ) and
A3: for e2 being Real st e2 > 0 holds
ex Y0 being finite Subset of X st
( not Y0 is empty & Y0 c= Y & ( for Y1 being finite Subset of X st Y0 c= Y1 & Y1 c= Y holds
|.(r2 - (setopfunc (Y1, the carrier of X,REAL,L,addreal))).| < e2 ) ) ; :: thesis: r1 = r2
A4: now :: thesis: for e3 being Real st e3 > 0 holds
|.(r1 - r2).| < e3
let e3 be Real; :: thesis: ( e3 > 0 implies |.(r1 - r2).| < e3 )
assume A5: e3 > 0 ; :: thesis: |.(r1 - r2).| < e3
set e4 = e3 / 2;
consider Y01 being finite Subset of X such that
not Y01 is empty and
A6: Y01 c= Y and
A7: for Y1 being finite Subset of X st Y01 c= Y1 & Y1 c= Y holds
|.(r1 - (setopfunc (Y1, the carrier of X,REAL,L,addreal))).| < e3 / 2 by A2, A5, XREAL_1:139;
consider Y02 being finite Subset of X such that
not Y02 is empty and
A8: Y02 c= Y and
A9: for Y1 being finite Subset of X st Y02 c= Y1 & Y1 c= Y holds
|.(r2 - (setopfunc (Y1, the carrier of X,REAL,L,addreal))).| < e3 / 2 by A3, A5, XREAL_1:139;
set Y00 = Y01 \/ Y02;
A10: ( (e3 / 2) + (e3 / 2) = e3 & Y01 c= Y01 \/ Y02 ) by XBOOLE_1:7;
A11: Y01 \/ Y02 c= Y by A6, A8, XBOOLE_1:8;
then |.(r2 - (setopfunc ((Y01 \/ Y02), the carrier of X,REAL,L,addreal))).| < e3 / 2 by A9, XBOOLE_1:7;
then ( |.((r1 - (setopfunc ((Y01 \/ Y02), the carrier of X,REAL,L,addreal))) - (r2 - (setopfunc ((Y01 \/ Y02), the carrier of X,REAL,L,addreal)))).| <= |.(r1 - (setopfunc ((Y01 \/ Y02), the carrier of X,REAL,L,addreal))).| + |.(r2 - (setopfunc ((Y01 \/ Y02), the carrier of X,REAL,L,addreal))).| & |.(r1 - (setopfunc ((Y01 \/ Y02), the carrier of X,REAL,L,addreal))).| + |.(r2 - (setopfunc ((Y01 \/ Y02), the carrier of X,REAL,L,addreal))).| < e3 ) by A7, A11, A10, COMPLEX1:57, XREAL_1:8;
hence |.(r1 - r2).| < e3 by XXREAL_0:2; :: thesis: verum
end;
r1 = r2
proof
assume A12: r1 <> r2 ; :: thesis: contradiction
A13: |.(r1 - r2).| <> 0
proof
assume |.(r1 - r2).| = 0 ; :: thesis: contradiction
then r1 - r2 = 0 by ABSVALUE:2;
hence contradiction by A12; :: thesis: verum
end;
0 <= |.(r1 - r2).| by COMPLEX1:46;
hence contradiction by A4, A13; :: thesis: verum
end;
hence r1 = r2 ; :: thesis: verum