This is a very good point, and one I think the author completely missed. I use bloom filters in an application at work and was very interested to hear about th

This is a very good point, and one I think the author completely missed. I use bloom filters in an application at work and was very interested to hear about this, wondering if some sort of hybrid might be useful. But when I saw that the hash map was storing the actual objects, I immediately dismissed the idea for my use case - we can't afford to store anything more than a handful of bits. (Our bloom filters set between 9 and 11 bits per signature.) The key advantage to bloom filters is that the represent set identity lookups (albeit in an adjustable lossy false-positive way). They do not, however, store actual sets of data. They must be coupled with a storage mechanism (traditionally with a several-order-of-magnitude slower lookup speed than the bloom filter) to actually store the items contained within the set - the bloom filter is just a way of definitively answering the question "Could this set possibly contain this item?"