0 Theorem 4, unlike Theorem 2, is not a s'pecial case of a known general result: it is not known if the statement of Theorem 4 holds for twoaccess channels that are not pairwise reversible. There is a converse to Theorem 4: For any fixed rate strictly inside R o , there exists a code with that rate for which X I 1 + o(N). This result holds for general twoaccess channels, and is proved by random...