Speaker: Takefumi Nosaka (Tokyo Institute of Technology)

Date and time: Tuesday, October 23, 5:15--6:30pm

Place: Gelman Library, room 608

Title: "Dijkgraaf-Witten invariants and Pachner moves"

Abstract: As a topological toy-model of the Chern-Simons invariant, Dijkgraaf and Witten suggested an invariant of 3-manifolds defined in a simple way. However, the computation is seemingly not so easy if done from definition. In this talk, I explain the definition and mention some technical difficulties. After that, I introduce some methods to compute the invariant. I will mention M. Wakui approach using Pachner moves on 3-manifolds

**:**

**Takefumi Nosaka**did his PhD under supervision of Tomotada Ohtsuki at RIMS at Kyoto University in 2012. Currently he is Assistant Professor at Department of Mathematics, Tokyo Institute of Technology. He has many nice results in Knot Theory and Quandle Theory and recently published a book: T. Nosaka, Quandles and Topological Pairs: Symmetry, Knots, and Cohomology, SpringerBriefs in Mathematics, November, 2017.