Abstracts

Week of September 13, 2026

September 14, 2026
Group Actions and Dynamics Several results about Patterson--Sullivan measures for relatively Anosov groups 4:10pm -
KT207

We prove that Patterson–Sullivan measures for relatively Anosov groups are exact dimensional with respect to visual metrics arising from suitable Gromov models. For relatively Morse groups, we further show that the scalar Cartan metric is Gromov hyperbolic, and hence induces a visual metric to which the exact dimensionality result applies. We also prove that the associated Manhattan manifolds are $C^1$-regular, and deduce that the growth indicator is $C^1$ and strictly concave on the interior of the limit cone. This is joint work with Eduardo Reyes.

Arithmetic Algebraic Geometry Some arithmetic aspects of the quantum connection 4:30pm -
KT 801

One can construct an A-model analogue of the Gauss-Manin connection using genus 0 Gromov-Witten invariants, which also make perfect sense over fields of positive characteristics and p-adic fields. I will explain how arithmetic gadgets including p-curvature, Fontaine-Laffaile modules, and over-convergent Frobenii (conjecturally) arise in this context, and discuss certain extensions in the q-difference setting based on quasimap K-theory. This is based on joint works with Lee, Pomerleano, and Seidel.

September 15, 2026
Geometric Analysis and Application Harmonic functions on three-dimensional manifolds 4:00pm to 5:00pm -
Kline Tower 801

The talk will present several properties of harmonic functions on three-dimensional complete noncompact manifolds with non-negative scalar curvature. Applications include volume bounds for geodesic balls, integral bounds for scalar curvature, and classification results. 

Geometric Representation Theory Seminar Spectral Action in Betti Metaplectic Langlands 4:30pm -
KT 207

Abstract: The metaplectic geometric Langlands program can be understood in two ways: as a twisted analogue of the geometric Langlands program, and as a geometric analogue of the Langlands program for covering groups, namely the metaplectic Langlands program. One of the key structures in the geometric Langlands program is the spectral action, which roughly says that the spectral side acts on the automorphic side, allowing one to spectrally decompose the automorphic category over the moduli of \check{G}-local systems. This can be viewed as a geometric incarnation of the automorphic-to-Galois direction.

 

One may hope that the spectral action carries over to the metaplectic setting, and this expectation was formulated by Gaitsgory and Lysenko under the name “metaplectic vanishing conjecture.” In this talk, I will discuss my recent work on constructing the spectral action in the Betti metaplectic context. I will focus on what changes in the metaplectic setting and on the categorical framework for studying factorizable actions of local systems of symmetric monoidal categories.

Geometric Representation Theory Seminar: https://sites.google.com/view/yale-grt-seminar/home

September 17, 2026
Analysis The Dry Ten Martini Problem for Sturmian Graphs 4:00pm -
KT 201

“Are all gaps there?” - a question originally posed by Mark Kac for the Almost-Mathieu operator and later termed the Dry Ten Martini Problem by Simon - asks whether all gap labels predicted by the Gap Labelling Theorem are attained by the integrated density of states. For the Almost-Mathieu operator, this problem has been resolved in almost all regimes, and for Sturmian Hamiltonians it was recently answered affirmatively, with all allowed gaps shown to be open. In this talk, we introduce a geometric analogue of this problem for operators on discrete and metric graphs generated by Sturmian subshifts, where the aperiodicity is encoded in the underlying graph structure rather than in a potential. We study ergodic Jacobi operators on such graphs and compute their gap labels explicitly. In contrast to the classical Sturmian Hamiltonians, we show that not all allowed gaps are open. The missing gaps arise from a geometric mechanism rather than a dynamical one: the local structure of the graph produces flat bands, leading to unattained gap labels. Based on joint work with Ram Band.

Geometry & Topology Pseudo-Anosov flows, hyperbolic geometry, and the curve graph 4:00pm to 5:00pm -
Kline Tower 221

In this talk, I will discuss a joint work with Samuel J. Taylor, where we consider embedded non-fiber surfaces in a closed hyperbolic 3-manifold transverse to a pseudo-Anosov flow. Utilizing foundational work on Kleinian surface groups, we connect the hyperbolic geometry of the surface to the dynamics of the flow via the curve graph. More specifically, the flow gives a pair of special multicurves on the surface, and we show that they are also geometrically distinguished, enabling us to extract geometric information, such as the position of short curves and the volume, from the relation of the pair of multicurves in the curve graph. Our result also connects to recent study of the geometry of endperiodic mapping tori.

September 18, 2026
Friday Morning Seminar Friday morning seminar 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00pm -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801
, 10:00am to 11:00am -
Kline Tower 801