reserve a,x,y for object, A,B for set,
  l,m,n for Nat;

theorem
  INT <> INT*
proof
  now
A1: {} in 1 by CARD_1:49,TARSKI:def 1;
    assume 1 in INT*;
    then ex x,y being object st {} = [x,y] by A1,RELAT_1:def 1;
    hence contradiction;
  end;
  hence thesis by INT_1:def 2;
end;
