We study error exponents for the problem of relaying a message over a tandem of two channels sharing the same transition law, in particular moving beyond the 1-bit setting studied in recent related works. Our main results show that the 1-hop and 2-hop exponents coincide in both of the following settings: (i) the number of messages is fixed, and the channel law satisfies a condition called pairwise reversibility, or (ii) the channel is arbitrary, and a zero-rate limit is taken from above. In addition, we provide various extensions of our results that relax the assumptions of pairwise reversibility and/or the two channels having identical transition laws, and we provide an example for which the 2-hop exponent is strictly below the 1-hop exponent.

翻译：我们研究在两个共享同一过渡法的渠道之间传递信息的问题的错误推理,特别是超越了最近相关著作中研究的一比位设置,我们的主要结果显示,一比二的推手在以下两种情况下都相吻合:(一) 电文的数量是固定的,频道法满足了一个称为双向可逆性的条件,或(二) 频道是任意的,上面取自一个零利率限制。此外,我们提供了我们结果的各种扩展,放松了对齐可逆性假设和(或)两个具有相同过渡法的频道,我们提供了一个例子,即二速的推手严格低于一比一的推手。