reserve n,k,b for Nat, i for Integer;

theorem Th2:
  for f being non empty XFinSequence holds f=<%f.0%> ^ (f/^1)
  proof
    let f be non empty XFinSequence;
    thus f=(f|1)^(f/^1) .= <%f.0%>^(f/^1) by Th1;
  end;
