Seminars and Colloquia by Series

Colored knot Floer homology

Series
Geometry Topology Seminar
Time
Monday, October 20, 2025 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Akram AlishahiUGA

Inspired by colored Khovanov homology, for any knot K in the 3-sphere, we define n-colored knot Floer homology as the limit of the cobordism maps from the (full) link Floer homology of the (n,mn)-cable of K to the (full) link Floer homology of  (n,(m+1)n)-cable as m goes to infinity. Colored knot Floer homology is graded by Alexander multi-grading and Maslov grading and it is finite dimensional at each fixed degree. We discuss the module structure of this invariant and overview some examples. This is a joint work with Eugene Gorsky and Beibei Liu.

The h-principle fails for prelegendrians in corank 2 fat distributions

Series
Geometry Topology Seminar
Time
Monday, October 13, 2025 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Eduardo FernándezUGA

It is a classical problem to study whether the h-principle holds for certain classes of maximally non-integrable distributions. The most studied case is that of contact structures, where there is a rich interplay between flexibility and rigidity, exemplified by the overtwisted vs tight dichotomy. For other types of maximally non-integrable distributions, no examples of rigidity are currently known.

In this talk I will discuss rigidity phenomena for fat distributions, which can be viewed as higher corank generalizations of contact structures. These admit natural symplectizations and contactizations. I will introduce a natural class of submanifolds in fat manifolds, called prelegendrians, which admit canonical Legendrian lifts to the contactization. The main result of the talk is that these submanifolds exhibit rigidity: in the “standard corank-2 fat manifold” there exists an infinite family of prelegendrian tori, all of them formally equivalent but pairwise not prelegendrian isotopic. In other words, the h-principle fails for prelegendrians. The talk is based on joint work with Álvaro del Pino and Wei Zhou.
 

Quantum invariants from linear algebra with diagrams

Series
Geometry Topology Seminar
Time
Monday, September 22, 2025 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Anup PoudelGeorgia Tech

We will look at various instances of how working with skeins (diagrams) provides a way to describe the existence of various topological quantum invariants that were originally described using representation theory. This provides a very simple description of these invariants. Along the way we will look at how to describe the algebraic data (ribbon categories) topologically and also how one could observe instances of certain dualities that exist between certain categories using these diagrams. 

Regular Lagrangians in Lefschetz fibrations

Series
Geometry Topology Seminar
Time
Monday, September 8, 2025 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Joe BreenUniversity of Alabama

Giroux and Pardon conjectured that a Lagrangian L in a Weinstein manifold W is regular (that is, compatible with the Weinstein structure in a natural sense) if there is a Lefschetz fibration p: W \to \C such that p(L) is a ray. In this talk, I will discuss forthcoming joint work with A. Roy and L. Wang, which establishes this conjecture. As an application of the proof, we show how all fillings of the rainbow closures of a positive braid can be described by manipulations of arcs in the base of an appropriate Lefschetz fibration.

Ribbon knots and iterated cables of fibered knots

Series
Geometry Topology Seminar
Time
Monday, August 25, 2025 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Jen HomGeorgia Tech

A knot is slice if it bounds a smoothly embedded disk in the four-ball and a knot is ribbon if it bounds such a disk with no local maxima. The slice-ribbon conjecture posits that every slice knot is ribbon. We prove that a linear combination of iterated cables of tight fibered knots is ribbon if and only if it is of the form K # -K, generalizing work of Miyazaki and Baker. Consequently, either iterated cables of tight fibered knots are linearly independent in the smooth concordance group, or the slice–ribbon conjecture fails.

Classification of knots vs. links in contact manifolds

Series
Geometry Topology Seminar
Time
Thursday, July 3, 2025 - 13:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Rima ChatterjeeOhio State University

 

A knot in a contact manifold is Legendrian if it is everywhere tangent to the contact planes. The classification problem in Legendrian knot theory has always generated significant interest. The problem gets a lot more complicated when we consider links. In this talk, I'll survey some of the results in this area and then discuss the classification problem for cable links of uniformly thick knot type.  If time permits, I'll also mention the classification of links in the overtwisted setting. Part of this is joint work with John Etnyre, Hyunki Min, and Tom Rodewald. 

TBD

Series
Geometry Topology Seminar
Time
Monday, April 21, 2025 - 14:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Diana HubbardBrooklyn College, CUNY

TBD

Cosmetic surgeries and Chern-Simons invariants

Series
Geometry Topology Seminar
Time
Monday, April 14, 2025 - 16:30 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Tye LidmanNorth Carolina State University

Dehn surgery is a fundamental construction in topology where one removes a neighborhood of a knot from the three-sphere and reglues to obtain a new three-manifold. The Cosmetic Surgery Conjecture predicts two different surgeries on the same non-trivial knot always gives different three-manifolds. We discuss how gauge theory, in particular, the Chern-Simons functional, can help approach this problem. This technique allows us to solve the conjecture in essentially all but one case. This is joint work with Ali Daemi and Mike Miller Eismeier.

Contact type hypersurfaces in small symplectic 4-manifolds

Series
Geometry Topology Seminar
Time
Monday, April 14, 2025 - 15:00 for 1 hour (actually 50 minutes)
Location
Skiles 006
Speaker
Tom MarkUniversity of Virginia

A codimension-1 submanifold embedded in a symplectic manifold is called “contact type” if it satisfies a certain convexity condition with respect to the symplectic structure. Given a symplectic manifold X it is natural to ask which manifolds Y can arise as contact type hypersurfaces. We consider this question in dimension 4, which appears much more constrained than higher dimensions; in particular we review evidence that no homology 3-sphere can arise as a contact type hypersurface in R^4 except the 3-sphere. We exhibit an obstruction for a contact 3-manifold to embed in certain closed symplectic 4-manifolds as the boundary of a Liouville domain---a slightly stronger condition than contact type---and explore consequences for the symplectic topology of small rational surfaces and potential applications to smooth 4-dimensional topology.

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