Turán number for odd-ballooning of trees

报告题目:Turán number for odd-ballooning of trees

报告人:陈耀俊 南京大学教授

报告时间:2023222(周三)上午 10:00-11:00 



      The Turán number ex(n,H) is the maximum number of edges in an H-free graph on n vertices. Let T be any tree. The odd-ballooning of T, denoted by To, is a graph obtained by replacing each edge of T with an odd cycle containing the edge, and all new vertices of the odd cycles are distinct. In this paper, we determine the exact value of ex(n, To) for sufficiently large n and To being good, which generalizes all the known results on ex(n, To) for T being a star, due to Erdős et al. (1995), Hou et al. (2018) and Yuan (2018), and provides some counterexamples with chromatic number 3 to a conjecture of Keevash and Sudakov (2004), on the maximum number of edges not in any monochromatic copy of H in a 2-edge-coloring of a complete graph of order n.


       陈耀俊,南京大学数学系教授,博士生导师。20007月在中国科学院数学与系统科学研究院获理学博士学位;2000.7-2002.6在南京大学数学系从事博士后研究工作;2003.9-2005.8在香港理工大学商学院物流系从事博士后研究工作;目前主要从事图中特定子图结构、Ramsey 理论、Turán数、图的定向以及理论计算机与组合图论交叉问题的研究。先后主持国家自然科学基金多项,在国内外专业学术杂志上发表研究论文80余篇。

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