Universal coding for the Slepian-Wolf data compression system and the strong converse theorem

Universal coding for the Slepian-Wolf (1973) data compression system is considered. We shall demonstrate based on a simple observation that the error exponent given by Csiszar and Korner (1980) for the universal coding system can strictly be sharpened in general for a region of relatively higher rates. This kind of observation can be carried over also to the case of lower rates outside the Slepian-Wolf region, which establishes the strong converse along with the optimal exponent