An Efficient Bit-Parallel Multi-Patterns Word Searching Algorithm through Splitting the Text

Abstract

Word matching problem is to find all the occurrences of a pattern P[0…m-1] in the text T[0…n-1], where P neither contains any white space nor preceded and followed by space. In the multi-patterns word matching problem, all the occurrences of multiple word P0, P1, P2 …Pr-1, (r≥1) in the given text T are to be reported. In the present discussion, we assume that all the patterns have equal size m and our text T is offline. We further assume that m ≤ w, where w is the word length of computer used. Ibrahiem et al. in 2008 have proposed an algorithm (WSA) for solving the word matching problem for single pattern by splitting the offline text into number of tables in the preprocessing phase. The main drawback of this algorithm was: after splitting the text into a number of tables, they search each occurrence of the pattern by the brute force manner in each table. In this paper, we extend this algorithm for multi-patterns word matching by using the technique of bit-parallel proposed by Baeza Yates, 1992. In this technique, after splitting the text into number of tables, we apply the shift-or algorithm to find the words of same length in the text T. The set of r multiple patterns is being handled by using the concept of classes of characters. This extended algorithm is called as multi-patterns word searching algorithm (MPWSA). Experimental results show that MPWSA algorithm is much faster than the previously proposed WSA algorithm.