e115 Nucleic Acids Research, 2005, Vol. 33, No. 13 44. Hyyr o¨,H. (2001) On using two-phase filtering in indexed approximate string matching with application to searching unique oligonucleotides. In Proceedings of String Processing and Information Retrieval (SPIRE 2001), November 13–15, Laguna de San Rafael, Chile, IEEE Press, pp. 84–95. 45. Levenshtein,V. (1966) Binary coded capable of correcting deletions, insertions and reversals. Soviet Phys. Doklady, 10, 707–710. 46. Myers,E. (1994) A sublinear algorithm for approximative keyword searching. Algorithmica, 12, 345–374. 47. Navarro,G. and Baeza-Yates,R. (2000) A hybrid indexing method for approximate string matching. J. Discrete Algorithms, 1, 205–239. PAGE 16 OF 16 48. Myers,G. (1999) A fast bit-vector algorithm for approximate string matching based on dynamic programming. J. ACM, 46, 539–553. 49. Chargaff,E. (1951) Structure and function of nucleic acids as cell constituents. Fed. Proc., 10, 654–659. 50. Karkas,J.D., Rudner,R. and Chargaff,E. (1968) Separation of B.subtilis DNA into complementary strands. II. Template functions and composition as determined by transcription with RNA polymerase. Proc. Natl Acad. Sci. USA, 60, 915–920. 51. Rudner,R., Karkas,J.D. and Chargaff,E. (1968) Separation of B.subtilis DNA into complementary strands. 3. Direct analysis. Proc. Natl Acad. Sci. USA, 60, 921–922.