Searching BWT Compressed Text with the Boyer-Moore Algorithm and Binary Search

This paper explores two techniques for on-line exact pattern matching in files that have been compressed using the Burrows-Wheeler transform. We investigate two approaches. The first is an application of the Boyer-Moore algorithm (Boyer & Moore 1977) to a transformed string. The second approach is based on the observation that the transform effectively contains a sorted list of all substrings of the original text, which can be exploited for very rapid searching using a variant of binary search. Both methods are faster than a decompress-and-search approach for small numbers of queries, and binary search is much faster even for large numbers of queries.