Nice one :) I don't see how range based would be more efficient than an accumulator though. The filters are designed to be an efficient representation of set, the false positive rate comes from the compression. @hal can you make two examples with the range based solution (like in negntropy) and a sync request based on a filter like a GCS filter? Make minimal examples (with 3 elements) and estamiate the size of the messages for both cases, example 1000 different elements in a set.