arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.01045cs.CC
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基于高维扩展器的局部可测码

Locally testable codes via high-dimensional expanders

Yotam Dikstein, Irit Dinur, Prahladh Harsha, Noga Ron-Zewi

摘要:

局部可测试码(LTC)是具有局部测试器的纠错码,该局部测试器可以通过仅在非常少(次线性,通常恒定)数量的位置处探测给定字来区分有效码字和远离所有码字的字。这些代码形成了PCP的组合骨架。一个主要的开放问题是是否存在LTC的积极率,恒定的相对距离和可测试的一个常数数量的查询。在本文中,我们提出了一种新的方法来构建这样的LTC使用的高维膨胀机的机械。为此,我们考虑的坦纳表示的代码,这是由一个图和一个基本的代码。非正式地说,我们的结果表明,如果这个图是一个高维扩展的一部分,那么代码的局部可测试性来自基本代码的局部可测试性。本文的工作统一和推广了子空间复形上Hadamard码、Reed-Muller码和提升码的可测性的已知结果,所有这些结果都是通过局部自校正得到的。然而,与以前的结果不同的是,恒定轮的自校正不足以作为基础的测试图的直径可以在高维扩展器中是巨大的,而不是恒定的,因为在所有已知的早期结果。我们克服了这一技术障碍,通过执行迭代自校正,具有几何上多轮,并严格控制在每次迭代中使用的高维扩展的属性的错误。鉴于这个结果,构建具有正速率和恒定相对距离的恒定查询LTC所缺少的成分是与恒定度高维扩展器良好交互的基本代码的实例化。

英文摘要:

Locally testable codes (LTC) are error-correcting codes that have a local tester which can distinguish valid codewords from words that are "far" from all codewords by probing a given word only at a very few (sublinear, typically constant) number of locations. Such codes form the combinatorial backbone of PCPs. A major open problem is whether there exist LTCs with positive rate, constant relative distance and testable with a constant number of queries. In this paper, we present a new approach towards constructing such LTCs using the machinery of high-dimensional expanders. To this end, we consider the Tanner representation of a code, which is specified by a graph and a base code. Informally, our result states that if this graph is part of a high-dimensional expander then the local testability of the code follows from the local testability of the base code. This work unifies and generalizes the known results on testability of the Hadamard, Reed-Muller and lifted codes on the Subspace Complex, all of which are proved via local self correction. However, unlike previous results, constant rounds of self correction do not suffice as the diameter of the underlying test graph can be logarithmically large in a high-dimensional expander and not constant as in all known earlier results. We overcome this technical hurdle by performing iterative self correction with logarithmically many rounds and tightly controlling the error in each iteration using properties of the high-dimensional expander. Given this result, the missing ingredient towards constructing a constant-query LTC with positive rate and constant relative distance is an instantiation of a base code that interacts well with a constant-degree high-dimensional expander.

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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