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Cameron-Liebler Line Classes, Tight Sets and Strongly Regular Cayley Graphs

发布时间:2022-03-21 作者: 浏览次数:
Speaker: 向青 DateTime: 2022年03月19日(周六)上午:10:00-11:00
Brief Introduction to Speaker:

  向青, 讲席教授。研究领域包括组合设计、有限几何、编码理论和加法组合。1995年毕业于俄亥俄州立大学,获博士学位。1999年获得国际组合数学及其应用协会颁发的Kirkman奖章。曾任美国加州理工学院Bateman Instructor, 美国特拉华(Delaware)大学终身教职,和浙江大学讲座教授。现为南方科技大学讲席教授。

Place: 腾讯会议号:417-720-663
Abstract: Abstract:Cameron-Liebler line classes are sets of lines in ${\rm PG}(3,q)$ having many interesting combinatorial properties. These line classes were first introduced by Cameron and Liebler in their study of collineation groups of ${\rm PG}(3,q)$ having the same number of orbits on points and lines of ${\rm PG}(3,q)$. During the past decade, Cameron-Liebler line classes have received considerable attention from researchers in both finite geometry and algebraic combinatorics. In the original paper \cite{camlie} by Cameron and Liebler, the authors gave several equivalent conditions for a set of lines of ${\rm PG}(3,q)$ to be a Cameron-Liebler line class; later Penttila gave a few more of such characterizations. We will use one of these characterizations as the definition of Cameron-Liebler line class. Let ${\mathcal L}$ be a set of lines of ${\rm PG}(3,q)$ with $|L|=x(q^2+ q+1)$, $x$ a positive integer. We say that ${\mathcal L}$ is a Cameron-Liebler line class with parameter $x$ if...