Approximate string matching using a bidirectional index.

We study strategies of approximate pattern matching that exploit bidirectional text indexes, extending and generalizing ideas of [9] . We introduce a formalism, called search schemes, to specify search strategies of this type, then develop a probabilistic measure for the efficiency of a search scheme, prove several combinatorial results on efficient search schemes, and finally, provide experimental computations supporting the superiority of our strategies. [ABSTRACT FROM AUTHOR]