A bit-parallel suffix automaton approach for (delta, gamma)-matching in music retrieval

Abstract

delta, gamma)-Matching is a string matching problem with applications to music retrieval. The goal is, given a pattern P-1...m and a text T-1...n on an alphabet of integers, find the occurrences P' of the pattern in the text such that (i) For All1 less than or equal to i less than or equal to m, \P-i - P-i'\ less than or equal to delta, and (ii) Sigma(1less than or equal toiless than or equal tom) \P-i - P-i'\ less than or equal to gamma. Several techniques for (delta, gamma)-matching have been proposed. In this paper we show that a classical string matching technique that combines bit-parallelism and suffix automata can be successfully adapted to this problem. This is the first character-skipping algorithm that skips characters using both delta and gamma. We implemented our algorithm and drew experimental results on real music showing that our algorithm is superior to current alternatives.