reserve i for Integer,
  a, b, r, s for Real;

theorem Th27:
  a <= b & r <= s implies the carrier of [:Closed-Interval-TSpace(
  a,b),Closed-Interval-TSpace(r,s):] = [: [.a,b.], [.r,s.] :]
proof
  set C1 = Closed-Interval-TSpace(a,b);
  set C2 = Closed-Interval-TSpace(r,s);
  assume a <= b & r <= s;
  then the carrier of C1 = [.a,b.] & the carrier of C2 = [.r,s.] by TOPMETR:18;
  hence thesis by BORSUK_1:def 2;
end;
