An Improvement in Lossless Data Compression via Substring Enumeration

Dube ´ and Beaudoin proposed a new technique of loss less data compression called compression via sub string enumeration (CSE) in 2010. It has been indicated that the compression ratio of CSE achieves competitive performance for ones of the best PPM variants and BZIP2 from the viewpoint of experimental results. We refine the technique of CSE to reduce the candidate value of range to encode, and make the compression performance of our improvement clear analytically for some input strings, which have zero entropy rate. We show that the performance of compression ratio of the improved CSE never becomes worse than one of the original CSE for any source string in linear-time and linear-space complexity for the length of string.