Seminars and Colloquia by Series

Poincaré Algorithm for Non-compact Lie Groups

Series
Geometry Topology Seminar
Time
Monday, February 24, 2025 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Yukun DuUniversity of Georgia

In this talk, I will present a geometric algorithm for determining whether a given set of elements in SO+(n,1) generates a discrete subgroup, as well as identifying the relators for the corresponding group presentation. The algorithm constructs certain hyperbolic manifolds that are always complete, a key condition for applying Poincaré Fundamental Polyhedron Theorem and ensuring the algorithm is valid. I will also introduce a generalization of this algorithm to the Lie group SL(n, R) and explore how the completeness condition extends to this broader setting.
 

Symmetries of Legendrian links and their exact Lagrangian fillings

Series
Geometry Topology Seminar
Time
Monday, January 27, 2025 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
James HughesDuke University

Given a Legendrian link L in the contact 3-sphere, one can hope to classify the set of exact Lagrangian fillings of L, i.e. exact Lagrangian surfaces in the symplectic 4-ball with boundary equal to L. Much of the recent progress towards this classification relies on establishing a connection between sheaf-theoretic invariants of Legendrians and cluster algebras. In this talk, I will describe this connection and how these invariants behave with respect to certain symmetries of Legendrian links and their fillings. Parts of this are joint work with Agniva Roy.

Strongly exceptional Legendrian connected sum of two Hopf links

Series
Geometry Topology Seminar
Time
Monday, January 13, 2025 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Youlin LiShanghai Jiao Tong University

In this talk, I will present a complete coarse classification of strongly exceptional Legendrian realizations of the connected sum of two Hopf links in contact 3-spheres. This is joint work with Sinem Onaran.

Dehn twist and smooth mapping class group of 4-manifolds

Series
Geometry Topology Seminar
Time
Monday, December 9, 2024 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Anubhav MukherjeePrinceton

In this talk, I will present recent advancements in the study of smooth mapping class groups of 4-manifolds. Our work focuses on diffeomorphisms arising from Dehn twists along embedded 3-manifolds and their interaction with Seiberg-Witten theory. These investigations have led to intriguing applications across several areas, including symplectic geometry (related to Torelli symplectomorphisms), algebraic geometry (concerning the monodromy of singularities), and low-dimensional topology (involving exotic diffeomorphisms). This is collaborative work with Hokuto Konno, Jianfeng Lin, and Juan Munoz-Echaniz.

Bounding non-integral non-characterizing Dehn surgeries

Series
Geometry Topology Seminar
Time
Monday, December 2, 2024 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Patricia SoryaUQAM

A Dehn surgery slope p/q is said to be characterizing for a knot K if the homeomorphism type of the p/q-Dehn surgery along K determines the knot up to isotopy. I discuss advances towards a conjecture of McCoy that states that for any knot, all but at most finitely many non-integral slopes are characterizing.

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