
theorem Th53:
  for a being Ordinal holds 1 -leading_coeff a = a
proof
  let a be Ordinal;
  not 1 in 1;
  hence 1 -leading_coeff a = a div^ exp(1 qua Ordinal, 0) by ORDINAL5:def 10
    .= a div^ 1 by ORDINAL2:43
    .= a by ORDINAL3:71;
end;
