The.Algorithm.Design.Manual.Springer-Verlag.1998

The.Algorithm.Design.Manual.Springer-Verlag.1998 The.Algorithm.Design.Manual.Springer-Verlag.1998

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Approximate String Matching Algorithms Mon Jun 2 23:33:50 EDT 1997 file:///E|/BOOK/BOOK5/NODE204.HTM (5 of 5) [19/1/2003 1:32:10]

Text Compression Next: Cryptography Up: Set and String Problems Previous: Approximate String Matching Text Compression Input description: A text string S. Problem description: A shorter text string S' such that S can be correctly reconstructed from S'. Discussion: Secondary storage devices fill up quickly on every computer system, even though their capacity doubles each year. Decreasing storage prices have only increased interest in data compression, since there is now more data to compress than ever before. Data compression is the algorithmic problem of finding alternative, space-efficient encodings for a given data file. With the rise of computer networks, a new mission for data compression has arisen, that of increasing the effective bandwidth of networks by reducing the number of bits before transmission. Data compression is a problem for which practical people like to invent ad hoc methods, designed for their particular applications. Sometimes these outperform general methods, but often they do not. The following issues arise in selecting the right data compression algorithm: ● Must we exactly reconstruct the input text after compression? - A primary issue in data compression algorithms is the question of lossy versus lossless encodings. Text applications typically demand lossless encodings, because users become disturbed whenever their data files file:///E|/BOOK/BOOK5/NODE205.HTM (1 of 4) [19/1/2003 1:32:11]

Approximate String Matching<br />

<strong>Algorithm</strong>s<br />

Mon Jun 2 23:33:50 EDT 1997<br />

file:///E|/BOOK/BOOK5/NODE204.HTM (5 of 5) [19/1/2003 1:32:10]

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