theorem Th8:
  for x being Element of {[0,{},{}],[1,{},{}]}
    holds JumpPart x = {}
 proof let x be Element of {[0,{},{}],[1,{},{}]};
   x = [0,{},{}] or x = [1,{},{}] by TARSKI:def 2;

  hence thesis;
 end;
