reserve s for set,
  i,j for Nat,
  c,c1,c2,c3 for Complex,
  F,F1,F2 for complex-valued FinSequence,
  R,R1,R2 for i-element complex-valued FinSequence;

theorem
  Sum(i |-> 0c) = 0c
proof
  thus Sum(i |-> 0c) = i*0 by Th36
    .= 0c;
end;
