Using T-codes as locally decodable source codes

A locally decodable source code (LDSC) allows the recovery of arbitrary parts of an unencoded message from its encoded version, using only a part of the encoded message as input, a challenge that arises when searching within compressed data sets. Simple source codes such as Huffman codes or Lempel-Z...

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Bibliographic Details
Main Authors: Speidel, Ulrich, Gulliver, T. Aaron, Medard, Muriel, Makhdoumi Kakhaki, Ali
Other Authors: Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Format: Article
Language:en_US
Published: Institute of Electrical and Electronics Engineers (IEEE) 2016
Online Access:http://hdl.handle.net/1721.1/100955
https://orcid.org/0000-0003-4059-407X
Description
Summary:A locally decodable source code (LDSC) allows the recovery of arbitrary parts of an unencoded message from its encoded version, using only a part of the encoded message as input, a challenge that arises when searching within compressed data sets. Simple source codes such as Huffman codes or Lempel-Ziv compression are not well suited to this task: A decoder starting at an arbitrary point within the compressed sequence generally cannot determine its position with respect to the boundaries between encoded symbols, or requires information found before the starting point in order to be able to decode. In this paper, we propose the use of subsets of self-synchronising variable-length T-codes as source codes and show that local decoding is feasible and practical using subsets of T-codes with bounded synchronisation delay (BSD).