New algorithms for regular expression matching

Abstract

In this paper we revisit the classical regular expression matching problem, namely, given a regular expression R and a string Q consisting of m and n symbols, respectively, decide if Q matches one of the strings specified by R. We present new algorithms designed for a standard unit-cost RAM with word length w ≥ log n. We improve the best known time bounds for algorithms that use O(m) space, and whenever w ≥ log 2 n, we obtain the fastest known algorithms, regardless of how much space is used. © Springer-Verlag Berlin Heidelberg 2006.