Fast approximate matching using suffix trees

Let T be a text of length n and P a pattern of length m, both strings over a fixed finite alphabet Sigma. We wish to find all approximate occurrences of P in T having weighted edit distance at most k from P: this is the approximate substring matching problem. We focus on the case in which T is fixed and preprocessed in linear time, while P and k vary over consecutive searches. We give an O(mq + t(occ)) time and O(q) space algorithm, where q less than or equal to n depends on the problem instance, and t(occ) is the size of the output. The running time is proportional to the amount of matching, in the worst case as fast as standard dynamic programming. The algorithm uses the suffix tree representation of the text. The best previous algorithm requires O(mq log q + t(occ)) time and O(mq) space.