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This web contains a record of most of my work in text data compression during the late 1980s and early 1990s. I created this web because the email I receive has shown that there is continued interest in these algorithms from students, academics and practitioners, and I thought it was about time I consolidated all my compression work into one well-organized resource. The algorithms I have created reside at opposite ends of the speed/compression tradeoff scale. From 1986 to 1989, while working towards my Ph.D., I researched text compression at the high-compression end of the scale and produced the SAKDC algorithm which was, to my knowledge, the highest-compression text compression algorithm in the world at the time. If you're interested in this high-compression algorithm, you may wish to take a look at my Ph.D. Thesis which was published as a book (which you can purchase online). Upon graduating, I decided to explore the other end of the scale and from 1990 to 1992 produced the LZRW series of algorithms which provided reasonable compression at very high speed. The LZRW1 algorithm is still one of the fastest known text compression algorithms. The high-compression (SAKDC, MMDC) algorithms were implemented in Ada under VAX/VMS using all sorts of obscure libraries and interfaces. This made their implementations appropriate for research experimentation only. In contrast most of the algorithms in the high-speed LZRW series were implemented in short sections of C code and, for a while, they became quite popular.
This web was created in a hurry in May 1996, but was not finished and placed online until August 1997. Future additions and changes to the web are likely to be just as sporadic. I will be creating a mailing list to which to post notice of such updates, but until then, the best thing you can do to stay up to date is to either check for changes every few months in the personalized change list on the RossNet Home Web, or register at The Registry. I will email all registrees when I get the mailing list web going. I hope that you enjoy the compression crypt. To get started take a look at the crypt Policy or surf the links at the top of this page.
Copyright © Ross N. Williams 1996-1997. All rights reserved. |