Can negligible cooperation increase network reliability?

In network cooperation strategies, nodes work together with the aim of increasing transmission rates or reliability. This paper demonstrates that enabling cooperation between the transmitters of a two-user multiple access channel via a cooperation facilitator that has access to both messages, always results in a network whose maximal- and average-error sum-capacities are the same - even when the information shared with the encoders is negligible. Thus, for a multiple access channel whose maximal- and average-error sum-capacities differ, the maximal-error sum-capacity is not continuous with respect to the output edge capacities of the facilitator. This shows that for some networks, sharing even a negligible number of bits per channel use with the encoders can yield a non-negligible benefit.