arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2206.03339math.CO
收藏

谱Erdens-Sós定理

A spectral Erdős-Sós theorem

Sebastian Cioabă, Dheer Noal Desai, Michael Tait

摘要:

著名的Erdens-Sós猜想指出,每个平均度大于$t-1$的图必须包含$t+1$顶点上的每棵树。在本文中,我们研究了这个猜想的谱版本。对于$n>k$,令$S_{n,k}$是$k$顶点上的团与$n-k$顶点的独立集合的连接,并用$S_{n,k}^+$表示通过添加一条边而从$S_{n,k}$获得的图。我们证明了对于固定的$k\geq 2$和足够大的$n$,如果一个图在$n$顶点上的邻接谱半径至少与$S_{n,k}$一样大,并且不同构于$S_{n,k}$,那么它包含所有在$2k+2$顶点上的树.类似地,如果一个足够大的图的谱半径至少与$S_{n,k}^+$一样大,那么它要么包含$2k+3$顶点上的所有树,要么同构于$S_{n,k}^+$。这肯定地回答了尼基福罗夫的两部分猜想。

英文摘要:

The famous Erdős-Sós conjecture states that every graph of average degree more than $t-1$ must contain every tree on $t+1$ vertices. In this paper, we study a spectral version of this conjecture. For $n>k$, let $S_{n,k}$ be the join of a clique on $k$ vertices with an independent set of $n-k$ vertices and denote by $S_{n,k}^+$ the graph obtained from $S_{n,k}$ by adding one edge. We show that for fixed $k\geq 2$ and sufficiently large $n$, if a graph on $n$ vertices has adjacency spectral radius at least as large as $S_{n,k}$ and is not isomorphic to $S_{n,k}$, then it contains all trees on $2k+2$ vertices. Similarly, if a sufficiently large graph has spectral radius at least as large as $S_{n,k}^+$, then it either contains all trees on $2k+3$ vertices or is isomorphic to $S_{n,k}^+$. This answers a two-part conjecture of Nikiforov affirmatively.

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。

↑