
theorem Th22:
  for n being set, S being non empty ZeroStr, b be bag of n holds
  (0_(n, S)).b = 0.S
proof
  let n be set, S be non empty ZeroStr, b be bag of n;
  b in Bags n by PRE_POLY:def 12;
  hence thesis by FUNCOP_1:7;
end;
