arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2009.05685cs.ITcs.CCmath.COmath.IT
收藏

Cayley图的线性Shannon容量

Linear Shannon Capacity of Cayley Graphs

Venkatesan Guruswami, Andrii Riazanov

摘要:

图的香农容量是零误差信息论中的一个基本量,用来度量图的幂中独立集的增长率。尽管研究得很好,但这个数量仍然有几个谜团。Lovász通过他的theta函数证明了$C_5$(5圈)的香农容量至多为$\sqrt{5}$。这个界限是通过一个简单的线性代码在$\mathbb{F}_5$映射$x \mapsto 2x$。这激发了图的线性香农容量的概念,这是当将自己限制为线性码时可实现的最大速率。基于多项式方法给出了$C_5$的线性Shannon容量为$\sqrt{5}$的简单证明。我们的方法适用于更一般的凯莱图添加剂组的有限域$\mathbb{F}_q$,给出了上界的线性香农容量。我们将此界限与Lovász theta函数进行比较,表明它们匹配自补Cayley图(如$C_5$),并且在某些情况下界限较小。我们还表现出线性和一般香农容量的一些图之间的二次差距。

英文摘要:

The Shannon capacity of a graph is a fundamental quantity in zero-error information theory measuring the rate of growth of independent sets in graph powers. Despite being well-studied, this quantity continues to hold several mysteries. Lovász famously proved that the Shannon capacity of $C_5$ (the 5-cycle) is at most $\sqrt{5}$ via his theta function. This bound is achieved by a simple linear code over $\mathbb{F}_5$ mapping $x \mapsto 2x$. This motivates the notion of linear Shannon capacity of graphs, which is the largest rate achievable when restricting oneself to linear codes. We give a simple proof based on the polynomial method that the linear Shannon capacity of $C_5$ is $\sqrt{5}$. Our method applies more generally to Cayley graphs over the additive group of finite fields $\mathbb{F}_q$, giving an upper bound on the linear Shannon capacity. We compare this bound to the Lovász theta function, showing that they match for self-complementary Cayley graphs (such as $C_5$), and that the bound is smaller in some cases. We also exhibit a quadratic gap between linear and general Shannon capacity for some graphs.

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。

↑