
theorem Th5:
  for n being Nat st n <> 1 ex p being Prime st p divides n
proof
  let n be Nat;
  assume
A2: n <> 1;
  per cases;
  suppose
    n is Prime;
    hence thesis;
  end;
  suppose
    not n is Prime;
    then ex p being Prime st p divides n & p <> n by A2,Th4;
    hence thesis;
  end;
end;
