PUB - Publikationen an der Universität Bielefeld

Almost two decades ago Ahlswede introduced an abstract correlated source (V x W, S) with outputs (v, w) is an element of S subset of v x W, where persons P-V and P-W observe v and w, respectively. More recently, Orlitsky considered the minimal number C-m of bits to be transmitted in m rounds to ''inform P-W about v over one channel.'' He showed that C-2 less than or equal to 4C(infinity)+3 and that in general C-2 not similar to C-infinity. We give a simple example for C-3 not similar to C-infinity. However, for the new model ''inform Pw over two channels,'' four rounds are optimal for this example-a result we conjecture in general. If both P-V and P-W are to be informed over two channels about the other outcome, we determine asymptotically the complexities for all sources. In our last model ''inform P-V and P-W over one channel'' for all sources the total number T-2 of required bits is known asymptotically and T-infinity is bounded from below in terms of average degrees. There are exact results for several classes of regular sources. An attempt is made to discuss the methods of the subject systematically.