Speaker: Shuxing Li received the Ph.D. degree in applied mathematics from Zhejiang University in 2016. Before joining University of Delaware in 2023 as an Assistant Professor, he was a Research Assistant with Hong Kong University of Science and Technology, an Alexander von Humboldt Post-Doctoral Fellow with Otto von Guericke University Magdeburg, and a Pacific Institute for the Mathematical Sciences Post-Doctoral Fellow with Simon Fraser University. His research interests include combinatorial design theory, algebraic coding theory, finite geometry, and the mathematics of communication. He serves on the editorial boards for Designs, Codes and Cryptography and Journal of Combinatorial Designs.

Date: January 20, 2026

Time: 15:30-16:30 pm

Location: E119, Huagang East Building, Shandong University Qingdao Campus

Sponsor: Research Center for Mathematics and Interdisciplinary Sciences, Shandong University

Abstract:

Consider a set P of permutations of [n] = {1, 2, …, n}, viewed as a set of ordered n-tuples. Assume that every ordered k-subsequence of distinct elements from [n] appears exactly λ times across the permutations in P. What is the minimum possible size of P? This natural question connects to directed t-designs, perfect deletion-correction codes, k-rankwise independent families of permutations, and a recent resurgence motivated by the introduction of perfect sequence covering arrays by Raphael Yuster. This talk presents recent progress on this problem, with an emphasis on a common group-based structure observed in certain perfect sequence covering arrays identified through sophisticated computer search.

This talk is based on joint work with Jonathan Jedwab and Jingzhou Na (Simon Fraser University).

For more information, please visit:

https://www.view.sdu.edu.cn/info/1020/209919.htm