[bdupras]

A few types of filters support deletion (e.g. counting bloom filters and cuckoo filters). To my knowledge all of them require prior knowledge that an entry was successfully inserted. That is, if you guess at deleting an entry and are successful, then you'll ruin the filter by creating a false-negative case.

As for collisions, only a limited number of colliding entries can be inserted into a cuckoo - after which a subsequent insertion will knowingly fail. So say Alice and Bob hash out to the same values, and you've inserted 2 Alices and 1 Bob. When you delete one Alice, it doesn't matter which entry is removed - two entries still remain that hash to Alice and Bob.

Perhaps the nuance you mention is that the alternate bucket index for an entry is calculated only from the fingerprint, not from the entry data. This has the effect that even when multiple entries share fingerprints, any one can be removed. (Again, _only_ if the system requesting the delete positively knows that the entry was previously successfully inserted.) The other colliding entry will still be found on query and will generate a "maybe" response.