That’s not a multiset, it’s a set containing tuples. A multiset (https://en.wikipedia.org/wiki/Multiset https://en.wikipedia.org/wiki/Multiset) allows you to ad

That’s not a multiset, it’s a set containing tuples. A multiset (https://en.wikipedia.org/wiki/Multiset https://en.wikipedia.org/wiki/Multiset) allows you to add identical items multiple times. You would use that to, for example, store the knowledge that 6 can be written as 3+3, by using a multiset {3,3} instead of a tuple (3,3)