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

Abstract : (δ,γ)-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) ∀ 1 ≤ i ≤ m, |P i  − P′ i | ≤ δ, and (ii) ∑ 1 ≤ i ≤ m |P i  − P′ i | ≤ γ. Several techniques for (δ,γ)-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 δ and γ. We implemented our algorithm and drew experimental results on real music showing that our algorithm is superior to current alternatives.