LINEAR-SPACE ALGORITHMS THAT BUILD LOCAL ALIGNMENTS FROM FRAGMENTS

This paper presents practical algorithms for building an alignment of two long sequences from a collection of ''alignment fragments,'' such as all occurrences of identical 5-tuples in each of two DNA sequences. We first combine a time-efficient algorithm developed by Galil and co workers with a space-saving approach of Hirschberg to obtain a local a lignment algorithm that uses O((M + N + F log N) log M) time and O(M N) space to align sequences of lengths M and N from a pool of F align ment fragments. Ideas of Huang and Miller are then employed to develop a time- and space-efficient algorithm that computes n best noninterse cting alignments for any n > 1. An example illustrates the utility of these methods.