theorem Th5: :: POLYNOM6:5

for o1, o2 being Ordinal
for b1 being Element of Bags o1
for b2 being Element of Bags o2 holds
( b1 +^ b2 = EmptyBag (o1 +^ o2) iff ( b1 = EmptyBag o1 & b2 = EmptyBag o2 ) )