Skip Navigation

The Computer Journal 1989 32(3):228-237; doi:10.1093/comjnl/32.3.228
© 1989 by British Computer Society
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (4)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Katajainen, J.
Right arrow Articles by Raita, T.
Right arrow Search for Related Content
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

An Approximation Algorithm for Space-optimal Encoding of a Text

J. Katajainen and T. Raita *

Department of Computer Science, University of Turku, SF-20520 Turku, Finland

In many situations text compression is carried out with a previously formed fixed dictionary (code book) expressing those often-occurring substrings of a text which are to be replaced by code words. The problem of encoding a text in a space-optimal manner is equivalent to the problem of finding a shortest path between a given pair of vertices in an acyclic and bandwidth-limited network. By combining an algorithm for finding shortest paths with the string matching algorithm of Aho and Corasick,1 a time-efficient approximation algorithm for the space-optimal encoding is obtained. The performance of the approximation algorithm depends on the amount of storage space available in the fast memory of a computer. With an unrestricted, though at most linear working storage on the length of the input text, a space-optimal encoding is obtained. However, even a fixed internal memory of moderate size guarantees almost optimal compression, and in spite of this the running time of the algorithm is comparable to that of the longest match heuristic.

Received April 1987.

* To whom corrrespondence should be addressed.

§ Department of Computer Science, University of Turku, SF-20520 Turku, Finland


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.