reserve T for TopSpace,
  A, B for Subset of T;

theorem Th35:
  for A, B being set holds A, B are_c=-incomparable or A c= B or B c< A
proof
  let A, B be set;
  assume that
A1: A, B are_c=-comparable and
A2: not A c= B and
A3: not B c< A;
  A c= B or B c= A by A1,XBOOLE_0:def 9;
  hence thesis by A2,A3,XBOOLE_0:def 8;
end;
