reserve n for Nat;

theorem
  for f be non empty FinSequence for g be FinSequence holds dom g c= dom (f^'g)
proof
  let f be non empty FinSequence;
  let g be FinSequence;
  len g <= len(f^'g) by TOPREAL8:9;
  hence thesis by FINSEQ_3:30;
end;
