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arXiv 1809.04716math.COcs.DM
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关于线性荫度猜想

Towards the linear arboricity conjecture

Asaf Ferber, Jacob Fox, Vishesh Jain

摘要:

图$G$的线性荫度,记为$\text{la}(G)$,是指$G$中边不相交的线性森林(即每个连通分支都是一条路的森林)的最小数目,其并集覆盖$G$的所有边。Akiyama、Exoo和Harary在1980年提出了一个著名的猜想:$\text{la}(G)\leq \lceil (Δ(G)+1)/2 \rceil$,其中$Δ(G)$表示$G$的最大度。这个严格的上界是最可能的,这可以通过将$G$看作一个正则图来容易地看出。在本文中,我们表明,对于每个图$G$,$\text{la}(G)\leq \fracΔ{2}+O(Δ^{2/3-α})$的一些$α> 0$,从而提高了以前最有名的界限,由于阿隆和斯宾塞从1992年。对于图是足够好的谱扩展,我们甚至更好的界限。我们的证明,这些结果进一步给出概率多项式时间算法找到这样的分解成线性森林。

英文摘要:

The linear arboricity of a graph $G$, denoted by $\text{la}(G)$, is the minimum number of edge-disjoint linear forests (i.e. forests in which every connected component is a path) in $G$ whose union covers all the edges of $G$. A famous conjecture due to Akiyama, Exoo, and Harary from 1980 asserts that $\text{la}(G)\leq \lceil (Δ(G)+1)/2 \rceil$, where $Δ(G)$ denotes the maximum degree of $G$. This conjectured upper bound would be best possible, as is easily seen by taking $G$ to be a regular graph. In this paper, we show that for every graph $G$, $\text{la}(G)\leq \fracΔ{2}+O(Δ^{2/3-α})$ for some $α> 0$, thereby improving the previously best known bound due to Alon and Spencer from 1992. For graphs which are sufficiently good spectral expanders, we give even better bounds. Our proofs of these results further give probabilistic polynomial time algorithms for finding such decompositions into linear forests.

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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