Study of Bit-Parallel Approximate Parameterized String Matching Algorithms

Abstract

In the parameterized string matching, a given pattern P is said to match with a substring t of the text T, if there exist a bijection from the symbols of P to the symbols of t. This problem has an important application insoftware maintenance, where we wish to find the equivalency between two sections of codes. Two sections of codes are said to be equivalent, if one can be transformed into the other by renaming identifiers and variables. In the approximate parameterized matching, a given pattern P matches the given substring t of the text T with k ≥ 0 errors, if P can be transformed into t with at most k modifications (insertion, deletion, replacement). In this paper, we extend Myers Bit-Parallel algorithm and Approximate String Matching by using Bit-Parallel NFA (both for approximate matching), for parameterized string matching problem. These extended algorithms are known as PAMA and PABPA respectively. Theoretically, PAMA algorithm is faster than PABPA algorithm. The above algorithms are applicable only when pattern length (m) is less than word length (w) of computer used (i.e. m ≤ w).