
theorem OPC:
  for a,b be non zero Integer holds
    Parity a, Oddity b are_coprime & (Parity a) gcd (Oddity b) = 1
  proof
    let a,b be non zero Integer;
    (Oddity b) gcd 2 = 1 by NEWTON03:def 5; then
    (Oddity b) gcd (2|^(2|-count a)) = 1 by WSIERP_1:12;
    hence thesis by Def1;
  end;
