theorem Th6:
  1 <= len (f:-p)
proof
  len(f:-p) = len(<*p*>^(f/^p..f)) by FINSEQ_5:def 2
    .= len<*p*> + len(f/^p..f) by FINSEQ_1:22
    .= 1 + len(f/^p..f) by FINSEQ_1:39;
  hence thesis by NAT_1:11;
end;
