Dartmouth Topology Seminar
Fall 2019–Spring 2020
Thursdays 11am-noon or 1:30-2:30 PM EDT
201 Kemeny Hall
Note: Special meeting times are marked in red.
Date Speaker Title
Apr. 22, 1:30pm Roman Golovko
(Charles University Prague)
Apr. 15, 1:30pm Juanita Pinzon-Caicedo
(University of Notre Dame)
Apr. 8, 1:30pm Patricia Cahn
(Smith College)
Feb. 11, 1:30pm Josh Howie
(UC Davis)
Feb. 4, 1:30pm Rima Chatterjee
Jan. 14, 11am Rustam Sadykov
Lusternik-Schnirelmann theory of 4-manifolds
Jan. 7, 11am Mikhail Tyomkin
(Higher School of Economics, Moscow)
Alexander polynomial of string links and Gassner matrix

April 22, 2021: Roman Golovko "TBA"


April 15, 2021: Juanita Pinzon-Caicedo "TBA"


April 8, 2021: Patricia Cahn "TBA"


February 11, 2021: Josh Howie "TBA"


February 4, 2021: Rima Chatterjee "TBA"


January 14, 2021: Rustam Sadykov "Lusternik-Schnirelmann theory of 4-manifolds"

Abstract: The Lusternik-Schnirelmann category of a topological space X is a minimal number of open sets U_i in a cover of X such that each set U_i is contractible in X. I will discuss various versions of the Lusternik-Schnirelmann category of 4-manifolds. In particular, I will discuss the relation of the Lusternik-Schnirlemann theory of 4-manifolds to Gay-Kirby trisections.
This is a joint work with Stanislav Trunov.

January 7, 2021: Mikhail Tyomkin "Alexander polynomial of string links and Gassner matrix"

Abstract: String link is a certain generalization of a pure braid, where we allow string to go upwards. One can define Alexander polynomial of a string link in the same manner as for the usual honest closed link in a 3-sphere. On the other hand, given string link L one can consider its closure \hat{L}, which is a closed link. We will discuss a formula which relates Alexander polynomials of L and \hat{L}. Namely, these two polynomials differ by a determinant of a Gassner matrix --- a certain invariant of a string link, which is interesting by itself. We assume no prerequisites.