arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1909.04264cs.ITmath.COmath.ITmath.MG
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广义表译码

Generalized List Decoding

Yihan Zhang, Amitalok J. Budkuley, Sidharth Jaggi

摘要:

本文关注的是一般对抗信道的列表解码问题,例如,位翻转($\textsf{XOR}$)通道、擦除通道、$\textsf{AND}$($Z$ -)通道、$\textsf{OR}$通道、实加法器通道、噪声打字机通道等。我们精确地表征了对于这些通道何时存在指数大小(或正速率)的$(L-1)$列表可解码码(其中列表大小$L$是通用常数)。我们的标准主张:“对于任何给定的一般对抗信道,当且仅当具有容许边缘的阶$L$的完全正张量的集合不完全包含在与该信道相关联的阶$L$混淆性集合中时,可以构造正速率$(L-1)$ -列表可解码码。“充分性是通过随机代码构造(结合删减或分时)来显示的。其必要性由1.使用超图Ramsey定理从任意大的码序列中提取等耦合子码(等距码的推广),以及2.利用完全正张量锥和共正张量锥之间的对偶性,将编码理论中的经典Plotkin界显著扩展到一般信道的列表解码。在证明中,我们还得到了一个关于联合分布不对称性的新事实,这可能是独立的利益。其他结果包括1。对于一般对抗性信道,使用渐进大的$L$列出解码容量; 2.一个严格的列表大小界大多数恒定的组合码(推广的恒定重量码); 3。Blinovsky [Bli 86]对列表解码Plotkin点(大代码不可能的阈值)的表征的重新推导和解密; 4.对纠错码设置中唯一解码的一般界限([WBBJ])进行评估。

英文摘要:

This paper concerns itself with the question of list decoding for general adversarial channels, e.g., bit-flip ($\textsf{XOR}$) channels, erasure channels, $\textsf{AND}$ ($Z$-) channels, $\textsf{OR}$ channels, real adder channels, noisy typewriter channels, etc. We precisely characterize when exponential-sized (or positive rate) $(L-1)$-list decodable codes (where the list size $L$ is a universal constant) exist for such channels. Our criterion asserts that: "For any given general adversarial channel, it is possible to construct positive rate $(L-1)$-list decodable codes if and only if the set of completely positive tensors of order-$L$ with admissible marginals is not entirely contained in the order-$L$ confusability set associated to the channel." The sufficiency is shown via random code construction (combined with expurgation or time-sharing). The necessity is shown by 1. extracting equicoupled subcodes (generalization of equidistant code) from any large code sequence using hypergraph Ramsey's theorem, and 2. significantly extending the classic Plotkin bound in coding theory to list decoding for general channels using duality between the completely positive tensor cone and the copositive tensor cone. In the proof, we also obtain a new fact regarding asymmetry of joint distributions, which be may of independent interest. Other results include 1. List decoding capacity with asymptotically large $L$ for general adversarial channels; 2. A tight list size bound for most constant composition codes (generalization of constant weight codes); 3. Rederivation and demystification of Blinovsky's [Bli86] characterization of the list decoding Plotkin points (threshold at which large codes are impossible); 4. Evaluation of general bounds ([WBBJ]) for unique decoding in the error correction code setting.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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