theorem
  for p being FinSequence of D st len p = 3 holds
  <*p*>@ = F2M p
  proof
    let p be FinSequence of D;
    assume
A1: len p = 3;
    then <*p*>@ = <* <* p.1 *>, <* p.2 *> , <* p.3 *> *> by Th63;
    hence thesis by A1,DEF1;
  end;
