theorem
  not ex y being object st [{},y] in RAT+
proof
  given y being object such that
A1: [{},y] in RAT+;
  consider i,j being Element of omega such that
A2: [{},y] = [i,j] and
A3: i,j are_coprime and
  j <> {} and
A4: j <> 1 by A1,Th29,Th32;
  i = {} by A2,XTUPLE_0:1;
  hence thesis by A3,A4,Th3;
end;
