reserve A for Tolerance_Space,
  X, Y for Subset of A;

theorem Th19:
  UAp {}A = {}
proof
  assume UAp {}A <> {};
  then consider x being object such that
A1: x in UAp {}A by XBOOLE_0:def 1;
  ex y being Element of A st y = x & Class (the InternalRel of A, y) meets
  {}A by A1;
  hence thesis;
end;
