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

theorem Th8:
  for x being object st x in LAp X holds Class (the InternalRel of A, x) c= X
proof
  let x be object;
  assume x in LAp X;
  then
  ex x1 being Element of A st x = x1 & Class (the InternalRel of A, x1) c= X;
  hence thesis;
end;
