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

theorem Th18:
  LAp {}A = {}
proof
  assume LAp {}A <> {};
  then consider x being object such that
A1: x in LAp {}A by XBOOLE_0:def 1;
  ex y being Element of A st y = x & Class (the InternalRel of A, y) c= {}A
  by A1;
  hence thesis by EQREL_1:20;
end;
