Title: Intriguing sets in distance regular graphs
Speaker: Stefaan de Winter (Associate Professor, Michigan State University)
Time: 10:00-11:00, Tuesday, May 8, 2018
Venue: 200-9, Sir Run Run Shaw Business Building, Yuquan Campus
Abstract: Tight sets were originally introduced in the 80s as special point sets in certain geometries. A slight generalization was introduced in the early 2000s, and includes such interesting objects as m-ovoids and Cameron-Liebler line classes. More recently the concept was further generalized to that of intriguing sets of distance regular graphs, and some small examples were obtained of such sets that are not tight sets. In joint work with Klaus Metsch we recently constructed the first infinite family of intriguing sets that are not tight sets (in the Grassmann graph of planes). Furthermore, we characterized our examples as the smallest possible examples in these graphs. In this talk I will first introduce all concepts, and provide some basic examples. Then I will give an overview of our recent results.