
theorem Th22:
  for f be Real_Sequence, n be Nat st f.0 = 0 holds
  Sum (f |_ Seg n) = (Partial_Sums f).n
  proof
    let f be Real_Sequence, n be Nat;
    assume
A1: f.0 = 0;
    Sum FinSeq (f,n) = (Partial_Sums f).n by A1,Th21;
    hence thesis by A1,Th18;
  end;
