theorem Th22:
  for p being Polynomial of L st p <> 0_.L holds len p-'1 = len p-1
  proof
    let p be Polynomial of L;
    assume p <> 0_.L;
    then 0 <> len p by POLYNOM4:5;
    then 0+1 <= len p by NAT_1:13;
    hence thesis by XREAL_1:233;
  end;
