theorem Th3:
  <*s*> is tabular
proof
  take len s;
  let x;
  assume x in rng <*s*>;
  then
A1: x in {s} by FINSEQ_1:38;
  then reconsider t=x as FinSequence by TARSKI:def 1;
  take t;
  thus thesis by A1,TARSKI:def 1;
end;
