A strong converse for a collection of network source coding problems

We prove a strong converse for particular source coding problems: the Ahlswede-Korner (coded side information) problem, lossless source coding for multicast networks with side-information at the end nodes, and the Gray-Wyner problem. Source and side-information sequences are drawn i.i.d. according to a given distribution on a finite alphabet. The strong converse discussed here states that when a given rate vector R is not D-achievable, the probability of observing distortion D for any sequence of block codes at rate R must decrease exponentially to 0 as the block length grows without bound. This strong converse implies the prior strong converses for the point-to-point network, Slepian-Wolf problem, and Ahlswede-Korner (coded side information) problem.