theorem
  for il being Nat, dl being Int-Location
  holds il <> dl
proof
  let il be Nat, dl be Int-Location;
  dl in  [:{1},NAT:] by AMI_2:def 16;
  then ex x,y being object st x in {1} & y in NAT & dl = [x,y] by ZFMISC_1:84;
 hence il <> dl;
end;
