theorem Th29:
  for m1,m2 being Multiset of D, a being Element of D holds
  (m1 [*] m2).a = (m1.a)+(m2.a)
proof
  reconsider N = <NAT,+,0> as non empty multMagma;
  let m1,m2 be Multiset of D, a be Element of D;
  reconsider f1 = m1, f2 = m2 as Element of .:(N,D);
  thus (m1 [*] m2).a = (f1.a)*(f2.a) by Th21
    .= (m1.a)+(m2.a) by MONOID_0:45;
end;
