[skip list](http://drum.lib.umd.edu/bitstream/handle/1903/544/CS-TR-2286.1.pdf;jsessionid=CCA235BC053E51DB6F7CAA89C0BD3616?sequence=2) [bloom filter](https://blog.medium.com/what-are-bloom-filters-1ec2a50c68ff) [count min](http://stackoverflow.com/questions/6811351/explaining-the-count-sketch-algorithm/35356116#35356116) [hyper log log ](http://algo.inria.fr/flajolet/Publications/FlFuGaMe07.pdf)
