Bottom-k document retrieval

We consider the problem of retrieving the k documents from a collection of strings where a given pattern P appears least often. This has potential applications in data mining, bioinformatics, security, and big data. We show that adapting the classical linear-space solutions for this problem is trivial, but the compressed-space solutions are not easy to extend. We design a new solution for this problem that matches the bestknown result when using 2|CSA|+ o(n) bits, where CSA is a Compressed Suffix Array. Our structure answers queries in the time needed by the CSA to find the suffix array interval of the pattern plus O(k lg k lg n) accesses to suffix array cells, for any constant > 0.