报告题目:Orientations of Graphs with Forbidden out-degree Lists Combinatorics of Eulerian-type polynomials
报告人: 吴河辉 研究员(上海数学中心)
报告时间:2022年4月7日(周四)下午14:30-15:30
报告地点:腾讯会议ID: 428-738-341
摘要:Let G be a graph and F: V(G)\mapsto 2^\mathbb{N} be a mapping. The graph G is said to be F- avoidable if there exists an orientation D of G such that for each vertex v, the out-degree d^+_D(v)\not\in F(v). It was conjectured by Akbari, Dalirrooyfard, Ehsani,Ozeki and Sherkati that if |F(v)|\le (d(v)-1)/2 for each vertex v, then G is F-avoiding , and they showed that |F(v)|\le d(v)/4 suffices. By using Combinatorial Nullestellensatz theorem, we improve the bound to |F(v)|\le [d(v)/3]. Furthermore, if the maximum degree is sub-exponentail of the minimum degree \delta, then if |F(v)|\le \(sqrt{2}-1-o(1))d(v)\approx (0.41+o(1))d(v) for each vertex v, then G is F-avaidable. This is joint work with Peter Bradshaw, Bojan Mohar in Simon Fraser University, and my students Yaobin Chen, Hao Ma in Fudan University.
报告人简介: 现任复旦大学上海数学中心青年研究员。2011 年在伊利诺伊大学获博士学位,师从 Douglas West 教授。2011 年至 2013 在 McGill 大学做博士后,指导教师是加拿大皇家院士 Bruce Reed 教授。2013-2014 在 Simon Fraser 大学任 PIMS 博士后,指导教授为 Bojan Mohar 教授。2014-2016 年任密西西比大学助理教授(Tenure Track)。2019 年入选上海市教委曙光学者计划。主要研究结构图论与极值组合,在 JCTB.,Comobinatorica,Forum of Mathematics-Sigma, SODA等高水平杂志或会议上发表多篇文章。现承担国家自然基金重点项目子项目1项。
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