A Source Model with Probability Distribution over Word Set and Recurrence Time Theorem(Source Cording/Image Processing)(<Special Section>Information Theory and Its Applications)

概要

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Nishiara and Morita defined an i. i. d. word-valued source which is defined as a pair of an i. i. d. source with a countable alphabet and a function which transforms each symbol into a word over finite alphabet. They showed the asymptotic equipartition property (AEP) of the i. i. d. word-valued source and discussed the relation with source coding algorithm based on a string parsing approach. However, their model is restricted in the i. i. d. case and any universal code for a class of word-valued sources isn't discussed. In this paper, we generalize the i. i. d. word-valued source to the ergodic word-valued source which is defined by an ergodic source with a countable alphabet and a function from each symbol to a word. We show existence of entropy rate of the ergodic word-valued source and its formula. Moreover, we show the recurrence time theorem for the ergodic word-valued source with a finite alphabet. This result clarifies that Ziv-Lempel code (ZL77 code) is universal for the ergodic word-valued source.
社団法人電子情報通信学会の論文
2003-10-01