theorem Th23:
  for L being non empty ZeroStr
  for p being constant Polynomial of L holds
  p = 0_.L or p = <%p.0%>
  proof
    let L be non empty ZeroStr;
    let p be constant Polynomial of L;
    deg p <= 0 by RATFUNC1:def 2;
    then len p - 1 + 1 <= 0 + 1 by XREAL_1:6;
    hence thesis by ALGSEQ_1:def 5;
  end;
