Optimal synchronous coding

作     者：Long, DY Jia, WJ Li, M 

作者机构：Zhongshan Univ Dept Comp Sci Guangdong 510275 Peoples R China Chinese Acad Sci State Key Lab Informat Secur Beijing 100039 Peoples R China City Univ Hong Kong Dept Comp Engn & Informat Technol Hong Kong Hong Kong Peoples R China E China Normal Univ Sch Informat Sci & Technol Shanghai 200062 Peoples R China 

出 版 物：《INTERNATIONAL JOURNAL OF COMPUTER MATHEMATICS》 (国际计算机数学杂志)

年 卷 期：2004年第81卷第8期

页      面：931-941页

核心收录：

学科分类：07[理学] 070104[理学-应用数学] 0701[理学-数学] 

基　　金：City U, (7001355) National Natural Science Foundation of China, NSFC, (60273062) National High-tech Research and Development Program, (2002AA144060) 

主　　题：data compression Huffman coding synchronous coding maximal prefix code optimal synchronous code 

摘      要：Novel synchronous coding schemes are introduced and relationships between optimal synchronous codes and Huffman codes are discussed. Although the problem of existence of the optimal synchronous codes has not yet resolved, we show that any synchronous code can be considered as an optimal synchronous code for some information source alphabet. In other words, synchronous codes are almost optimal and, therefore, are regarded as near optimal with respect to average code word length. It is shown that there always exist optimal synchronous codes for the information source alphabets with a dyadic probability distribution. Comparing with the Huffman coding, the synchronous coding is used not only for statistical modeling but also for dictionary methods. It is also good at using in a large information retrieval system like the Huffman coding. Moreover, from the viewpoint of computational difficulty, it is proven that breaking a synchronous or an optimal synchronous code is NP-complete.