D. T. Hoang,
P. M. Long and J. S. Vitter.
Dictionary selection using partial matching. Information
Sciences, 119(1-2):57-72, 1999. (Available in Postscript and PDF formats.)
Abstract
This work concerns the search for text compressors that compress
better than existing dictionary
coders, but run faster than statistical coders. We describe
a new method for text compression
using multiple dictionaries, one for each context of
preceeding characters, where the contexts have
varying lengths. The context to be used is determined
using an escape mechanism similar to that
of PPM methods. We describe modifications of three
popular dictionary coders along these lines
and experiments evaluating their effectiveness
using the text files in the Calgary corpus. Our
results suggest that modifying LZ77, LZFG, and LZW
along these lines yields improvements in
compression of about 3%, 6%, and 15%, respectively.