A new parameterized string matching algorithm by combining bit-parallelism and suffix automata

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 in software 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 only. Crochemore et al., 1994, has developed an algorithm (BDM) for exact string matching problem using suffix automata. Kimmo Fredriksson et al., 2006, has developed parameterized bit-parallel algorithm (parameterized shift-or) and parameterized BDM (PBDM). Parameterized shift-or (PSO) simulates finite automata in their nondeterministic form. The main drawback of PSO is: it is unable to skip text characters while matching forward. In this paper, we develop a new algorithm for parameterized string matching problem. This algorithm is based upon both suffix automata and bit parallelism concepts. This algorithm is faster than PBDM, since it processes the suffix automata in their non-deterministic form.