Weak variable-length Slepian-Wolf coding with linked encoders for mixed sources

Slepian and Wolf (see IEEE Trans. Inform. Theory, vol.19, p.471-80, July 1973) first considered the data compression of correlated sources called the SW system, where two sequences emitted from correlated sources are separately encoded to codewords, and sent to a single decoder which has to output original sequence pairs. Recently, Oohama (see IEEE Trans. Inform. Theory, vol.42, p.837-47, May 1996) has extended the SW system and investigated a more general case where there are some mutual linkages between two encoders of the SW system. In this paper, we investigate variable-length coding which allows asymptotically vanishing probability of error for the system considered by Oohama. We clarify the admissible rate region for mixed sources characterized by two ergodic sources, and show that this region is strictly wider than that for fixed-length codes.