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Density and spanning trees of A-connected graphs

Prof. Rong Luo(罗荣 教授)
2016-3-20 10:00-11:00  闵行数学楼126室
 
报告人简介:
罗荣教授是美国West Virginia University 数学系教授,国际知名图论研究专家。他主要研究兴趣在图的整数流、图的染色、图的连通性等图论重要研究领域,发表了40多篇学术论文,多发表在J. of Combin. Theory (B)、Euorp. J. Combin、SIAM J. Discret. Math等组合图论领域顶尖期刊上。

报告内容简介:
Let A be an Abelian group. It is known that an A-connected graph cannot be very sparse. We study the extremal problem: find the maximum integer k, denoted ex(n, A), such that every graph with at most k edges is not A-connected. We determine the exact values for all finite cyclic groups. As a corollary, we present a characterization of all Z_k-connected graphic sequences. It is also known that there are Z_5-connected graph that are not Z_6-connected. We prove that every Z_3-connected graph contains two edge-disjoint spanning trees, which implies that every Z_3-connected graph is also A-connected for any A with order at least 4.

主持人:吕长虹 教授

数学系
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