
theorem
  for f be INT-valued Real_Sequence, n be Nat st f.0 = 0 holds
  Sum (f |_ Seg n) is Integer
  proof
    let f be INT-valued Real_Sequence, n be Nat;
    assume
A1: f.0 = 0;
    set ff = f |_ Seg n;
    Sum ff = (Partial_Sums f).n by Th22,A1;
    hence thesis;
  end;
