On the deterministic code capacity region of an arbitrarily varying multiple-access channel under list decoding

We study the capacity region C_L of an arbitrarily varying multiple-access channel (AVMAC) for deterministic codes with decoding into a list of a fixed size L and for the average error probability criterion. Motivated by known results in the study of fixed size list decoding for a point-to-point arbitrarily varying channel, we define for every AVMAC whose capacity region for random codes is nonempty, a nonnegative integer U called its symmetrizability. It is shown that for every L ≤ U, C_L has an empty interior, and for every L ≥ (U +1)², C_L equals the capacity region of the AVMAC for random codes with a known single-letter characterization.