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Damaged BZip Files Are Difficult to Repair

  • Christian Hundt
  • Ulf Ochsenfahrt
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5092)

Abstract

bzip is a program written by Julian Seward that is often used under Unix to compress single files. It splits the file into blocks which are compressed individually using a combination of the Burrows-Wheeler-Transformation, the Move-To-Front algorithm, Huffman and Runlength encoding. The author himself stated that compressed blocks that are damaged, i.e., part of which are lost, are essentially non-recoverable. This paper gives a formal proof that this is indeed true: focusing on the Burrows-Wheeler-Transformation, the problem of completing a transformed string, such that the decoded string obeys certain file format restrictions, is NP-hard.

Keywords

Bipartite Graph Hamiltonian Cycle Original Graph Outgoing Edge Input String 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    Brandstädt, A., Le, V.B., Spinrad, J.P.: Graph Classes; A Survey. SIAM Monographs on Discrete Mathematics and Applications (1999)Google Scholar
  2. 2.
    Burrows, M., Wheeler, D.J.: A Block-sorting Lossless Data Compression Algorithm. SRC Research Report (1994)Google Scholar
  3. 3.
    Garey, M.R., Johnson, D.S.: Computers and Intractability; A Guide to the Theory of NP-Completeness. W. H. Freeman & Co., New York (1979)zbMATHGoogle Scholar
  4. 4.
    Hopcroft, J.E., Motwani, R., Ullman, J.D.: Introduction to Automata Theory, Languages, and Computation. Addison-Wesley, Reading (2000)Google Scholar
  5. 5.
    Seward, J.: - The official BZip Homepage, http://www.bzip.org

Copyright information

© Springer-Verlag Berlin Heidelberg 2008

Authors and Affiliations

  • Christian Hundt
    • 1
  • Ulf Ochsenfahrt
    • 1
  1. 1.Fakultät für Informatik und ElektrotechnikUniversität RostockGermany

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