
theorem
  for b being Ordinal holds b -leading_coeff 1 = 1
proof
  let b be Ordinal;
  per cases by ORDINAL1:14;
  suppose 1 in b;
    hence thesis by Th55;
  end;
  suppose 1 = b;
    hence thesis by Th53;
  end;
  suppose b in 1;
    then b = 0 by TARSKI:def 1, CARD_1:49;
    hence thesis by Th52;
  end;
end;
