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Prefix codes: Equiprobable words, unequal letter costs

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Automata, Languages and Programming (ICALP 1994)

Part of the book series: Lecture Notes in Computer Science ((LNCS,volume 820))

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Abstract

We consider the following variant of Huffman coding in which the costs of the letters, rather than the probabilities of the words, are non-uniform: Given an alphabet of unequal-length letters, find a minimum-average-length prefix-free set of n codewords over the alphabet. We show new structural properties of such codes, leading to an O(n log2 r) time algorithm for finding them. This new algorithm is simpler and faster than the previously best known O(nr min{log n, r}) one due to Perl, Garey, and Even [5].

Partially supported by HK RGC Competitive Research Grant HKUST 181/93E.

Partially supported by NSF grants CCR-8906949 and CCR-9111348.

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References

  1. Doris Altenkamp and Kurt Melhorn. Codes: Unequal probabilies, unequal letter costs. Journal of the Association for Computing Machinery, 27(3):412–427, July 1980.

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  2. D. A. Huffman. A method for the construction of minimum redundancy codes. In Proc. IRE 40, volume 10, pages 1098–1101], September 1952.

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  3. Richard Karp. Minimum-redundancy coding for the discrete noiseless channel. IRE Transactions on Information Theory, January 1961.

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  4. Donald E. Knuth. The Art of Computer Programming, Volume III: Sorting and Searching Addison-Wesley, Reading, Mass., 1973.

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  5. Y. Perl, M. R. Garey, and S. Even. Efficient generation of optimal prefix code: Equiprobable words using unequal cost letters. Journal of the Association for Computing Machinery, 22(2):202–214, April 1975.

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Authors and Affiliations

  1. Hong Kong UST, Clear Water Bay, Kowloon, Hong Kong

    Mordecai J. Golin

  2. UMIACS, University of Maryland, 20742, College Park, MD

    Neal Young

Authors
  1. Mordecai J. Golin
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  2. Neal Young
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Serge Abiteboul Eli Shamir

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© 1994 Springer-Verlag Berlin Heidelberg

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Golin, M.J., Young, N. (1994). Prefix codes: Equiprobable words, unequal letter costs. In: Abiteboul, S., Shamir, E. (eds) Automata, Languages and Programming. ICALP 1994. Lecture Notes in Computer Science, vol 820. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-58201-0_102

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  • DOI: https://doi.org/10.1007/3-540-58201-0_102

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  • Publisher Name: Springer, Berlin, Heidelberg

  • Print ISBN: 978-3-540-58201-4

  • Online ISBN: 978-3-540-48566-7

  • eBook Packages: Springer Book Archive

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