| 个人简介 | |
|---|---|
 Prof. Jacobus Koolen University of Science and Technology of China, Netherlands |
|
| 标题： Bounding the intersection number $c_2$ for thin $Q$-polynomial distance-regular graphs | |
| 摘要： In the survey paper by Van Dam, Tanaka and the speaker they asked the following question:Let $b\geq 1$ be a rational number. Does there exists a function $f(b)$ in $b$ such that if $\Gamma$ is with $\frac{b_1}{\theta_1 +1} = b$ where $\theta_1 is the second largest eigenvalue of $\Gamma$, then its intersection number $c_2$ is bounded by $f(b)$. We show it for a class of thin $Q$-polynomial distance-regular graphs. This is joint work with Y. Tan, M. Cao and J. Park. | |
| 简介： Jack Koolen is currently a full professor at the University of Science and Technology of China. He received his Ph.D. from Eindhoven University of Technology in 1994 under supervision of Prof Andries Brouwer. After a few post doc positions in for example Oxford University and Kyushu University, he became an associate professor in POSTECH in Pohang Korea. Since 2013 he is a full professor at the University of Science and Technology of China. His main interest is in algebraic graph theory especially distance-regular graphs. Recently he also got interested in graphs with fixed smallest eigenvalues. He has co-authored a book on phylogenetic combinatorics. | |
