theorem Th2:
  for p being FinSequence holds p <> {} implies
  ex q being FinSequence, x st p = q^<*x*> & len p = len q + 1
proof
  let p be FinSequence;
  assume p <> {};
  then consider q being FinSequence, x being object such that
A1: p = q^<*x*> by FINSEQ_1:46;
  take q, x;
  len p = len q + len <*x*> by A1,FINSEQ_1:22
    .= len q + 1 by FINSEQ_1:40;
  hence thesis by A1;
end;
