
theorem Th13:
  for b be complex-valued FinSequence
    st len b = 1 holds Product b = b.1
  proof
    let b be complex-valued FinSequence;
    assume len b = 1; then
    b = <*b.1*> by FINSEQ_1:40;
    hence Product b = b.1 by RVSUM_1:95;
  end;
