On using q-gram locations in approximate string matching

Abstract

Approximate string matching with k differences is considered. Filtration of the text is a widely adopted technique to reduce the text area processed by dynamic programming. A sublinear filtration algorithm is presented. The method is based on the locations of the q-grams in the pattern. Samples of q-grams are drawn from the text at fixed periods, and only if consecutive samples appear in the pattern approximately in the same configuration, the text area is examined with dynamic programming. Practical experiments show that this approach gives better filtration efficiency than an earlier method.