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Week of February 1, 2026

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February 2, 2026
Geometric Analysis and Application [3] Minimal submanifolds, higher expanders, and waists of locally symmetric spaces Ben Lowe - University of Chicago 3:45pm -
KT 906
Geometry, Symmetry and Physics [4] Stable homology of moduli spaces, and moments of families of quadratic L-functions over function fields Dan Petersen - Stockholm and IAS 4:30pm -
KT 801
February 5, 2026
Analysis [5] Asymptotic linear stability of a class of columnar flow Shuang Miao - Wuhan University 4:00pm -
KT 201
Quantum Topology and Field Theory [6] Skein valued cluster theory and open Gromov-Witten invariants Mingyuan Hu - Northwestern University 4:00pm -
KT 801
February 6, 2026
Learning seminar on Matroids and Algebraic Cycles [7] Learning seminar on Matroids and Algebraic Cycles 2:15pm -
KT 801
Learning seminar on Groups, Geometry and Dynamics [8] Ergodicity of geodesic flow and the Hopf argument. Sebastian Hurtado - 4:00pm -
KT801 (or KT 217).
February 9, 2026
Geometric Analysis and Application [3] Widths, Index, Intersection, and Isospectrality Jared Marx-Kuo - Rice University 3:45pm -
KT 906
Geometry, Symmetry and Physics [4] Stabilization of Kac polynomials along root strings Vladyslav Zveryk - Yale University 4:30pm -
KT801
February 10, 2026
Geometric Analysis Learning Seminar [9] Geometric Analysis Learning Seminar 10:30am -
KT 801
Group Actions, Geometry and Dynamics [10] The pentagram zoo Max Weinreich - Harvard University 4:30pm -
KT 203
February 12, 2026
Analysis [5] Support of semiclassical measures in higher dimensions Elena Kim - MIT 4:00pm -
KT 201
Quantum Topology and Field Theory [6] Relationships between skein algebras Helen Wong - Claremont McKenna College 4:30pm -
KT 801
February 13, 2026
Learning seminar on Matroids and Algebraic Cycles [7] Learning seminar on Matroids and Algebraic Cycles 2:15pm -
KT 801
Learning seminar on Groups, Geometry and Dynamics [8] Coding of hyperbolic diffeomorphisms. Ethan Cohen - 4:00pm -
KT 217
February 16, 2026
Geometric Analysis and Application [3] On Backwards uniqueness for singular mean curvature flows. Or Hershkovits - University of Maryland 3:45pm -
KT 906
Geometry, Symmetry and Physics [4] Virtual Hodge numbers of the moduli space of maps to projective space Siddarth Kannan - MIT 4:30pm -
KT 801
February 17, 2026
Geometry & Topology [11] Superrigidity of rich representations Alex Maldague - Rice University 4:30pm -
KT 207
February 19, 2026
Quantum Topology and Field Theory [6] Skeins, q-series, and modularity Sunghyuk Park - CMSA Harvard 4:30pm -
KT 801
February 20, 2026
Learning seminar on Matroids and Algebraic Cycles [7] Learning seminar on Matroids and Algebraic Cycles 2:15pm -
KT 801
February 23, 2026
Geometric Analysis and Application [3] Splitting a manifold with (spectral) Ricci lower bounds Gioacchino Antonelli - University of Notre Dame 3:45pm -
February 24, 2026
Geometric Analysis Learning Seminar [9] Geometric Analysis Learning Seminar 10:30am -
KT 801
Geometry, Symmetry and Physics [4] Graded characters of Verma modules via the sphere trace Daniil Kliuev - Northwestern 10:30am -
KT 329
February 25, 2026
Group Actions and Dynamics [12] Random Walks on the Group of Planar Isometries and Local Limit Theorems Reuben Drogin - Yale University 4:00pm -
KT205
February 26, 2026
Analysis [5] Critical collapse in 2+1 gravity Şerban Cicortaş - Princeton University 4:00pm -
KT 201
Quantum Topology and Field Theory [6] Finite N indices from branes and negative branes Kasia Budzik - Harvard 4:30pm -
KT 801
February 27, 2026
Learning seminar on Matroids and Algebraic Cycles [7] Learning seminar on Matroids and Algebraic Cycles 2:15pm -
KT 801
Learning seminar on Groups, Geometry and Dynamics [8] Learning seminar on Groups Geometry and Dynamics Sebastian Hurtado - 4:00pm -
KT 801 or KT217

Abstracts

Week of February 1, 2026

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February 2, 2026
Geometric Analysis and Application [3] Minimal submanifolds, higher expanders, and waists of locally symmetric spaces 3:45pm -
KT 906

There is by now a broad body of work on minimal surfaces in positively curved ambient manifolds. If the ambient manifold has nonpositive curvature, much less is known. I will present some recent results on minimal submanifolds in nonpositively curved locally symmetric spaces, that are motivated by or have parallels to the positive curvature setting. The proofs bring new tools into the picture from representation theory. Another key ingredient is a new monotonicity formula for minimal submanifolds of low codimension in nonpositively curved symmetric spaces. 

I will then discuss applications to a program initiated by Gromov to prove statements of the following kind: Suppose we are given two manifolds X and Y, where X is “complicated” and Y is lower dimensional. Then any map f: X-> Y must have at least one “complicated” fiber. If time permits, I will also discuss some applications to systolic geometry, global fixed point statements for actions of lattices on contractible CAT(0) simplicial complexes, and/or non-abelian higher expansion and branched cover stability.  

Geometry, Symmetry and Physics [4] Stable homology of moduli spaces, and moments of families of quadratic L-functions over function fields 4:30pm -
KT 801

This is a report of joint work with Bergström-Diaconu-Westerland and Miller-Patzt-Randal-Williams. There is a “recipe” due to Conrey-Farmer-Keating-Rubinstein-Snaith which allows for precise predictions for the asymptotics of moments of many different families of L-functions. We consider the family of all L-functions attached to hyperelliptic curves over some fixed finite field. One can relate this problem to understanding the homology of the moduli space of hyperelliptic curves, with symplectic coefficients. With Bergström-Diaconu-Westerland we compute these stable homology groups, together with their structure as Galois representations. With Miller-Patzt-Randal-Williams we prove a uniform range for homological stability. Together, these results imply the CFKRS predictions for all moments in the function field case, for all sufficiently large (but fixed) q.

February 5, 2026
Analysis [5] Asymptotic linear stability of a class of columnar flow 4:00pm -
KT 201

Constructing dynamical global-in-time solutions to 3D incompressible Euler equation is in general challenging. Recently Guo-Pausader-Widmayer made a breakthrough in this direction by proving asymptotic stability of a uniform-rotating static solution. Their approach heavily depends on the “uniform-rotating” of the background solution. In this talk I will present some recent progress on asymptotic linear stability of a more general columnar flow with non-uniform rotation. This is a joint work with Siqi Ren (Zhejiang U of Technology) and Zhifei Zhang (Peking U).

Quantum Topology and Field Theory [6] Skein valued cluster theory and open Gromov-Witten invariants 4:00pm -
KT 801

For a Lagrangian submanifold in a CY3, Ekholm and Shende defined a wavefunction living in the HOMFLY-PT skein module of the Lagrangian, which encodes open Gromov-Witten invariants in all genus. In this talk, we study a skein-valued cluster theory that generalizes quantum cluster theory and allows us to compute these wavefunctions in a range of examples. Our results agree with the physical prediction known as the topological vertex. Along the way we introduce a skein dilogarithm and prove a pentagon relation, generalizing previously known forms of the pentagon identity. This talk is based on joint works with Schrader, Zaslow, and Shende.

February 6, 2026
Learning seminar on Matroids and Algebraic Cycles [7] Learning seminar on Matroids and Algebraic Cycles 2:15pm -
KT 801

TBA

Learning seminar on Groups, Geometry and Dynamics [8] Ergodicity of geodesic flow and the Hopf argument. 4:00pm -
KT801 (or KT 217).

We will discuss  the ergodicity of anosov diffeomorphisms and the geodesic flow in negative curvature, talk about pathological foliations and Fubini’s nightmare. 

February 9, 2026
Geometric Analysis and Application [3] Widths, Index, Intersection, and Isospectrality 3:45pm -
KT 906

In this talk, I will discuss a series of works on Gromov’s p-widths, $\{\omega_p\}$, on surfaces. For ambient dimensions larger than $2$, $\omega_p$ morally realizes the area of an embedded minimal surface of index p. This characterization was historically used to prove the existence of infinitely minimal hypersurfaces in closed Riemannian manifolds. In ambient dimension $2$, $\omega_p$ realizes the length of a union of (potentially immersed) geodesics, and heuristically, $p$ is equal to the sum of the indices of the geodesics plus the number of points of self-intersection. Joint with Lorenzo Sarnataro and Douglas Stryker, we prove upper bounds on the index and vertices, making progress towards this heuristic. Along the way, we prove a generic regularity statement for immersed geodesics. If time allows, we will also discuss the isospectral problem for the p-widths and how surfaces provide a convenient setting to investigate this. 

Geometry, Symmetry and Physics [4] Stabilization of Kac polynomials along root strings 4:30pm -
KT801

In this talk, I will present the stabilization phenomenon of cohomology groups and Kac polynomials associated with moduli spaces of quiver representations. Specifically, for Q and chosen dimension vectors d and e satisfying reasonable conditions, the cohomologies of various types of quiver varieties associated with dimension vectors d+ne stabilize as e tends to infinity. I will provide explicit generating functions for these stabilized dimensions and explain the implications for root multiplicities of Kac-Moody Lie algebras.

February 10, 2026
Geometric Analysis Learning Seminar [9] Geometric Analysis Learning Seminar 10:30am -
KT 801

TBA

Group Actions, Geometry and Dynamics [10] The pentagram zoo 4:30pm -
KT 203

Schwartz’s pentagram map is a dynamical system defined on moduli spaces of polygons by intersecting diagonals. It is an integrable system, meaning that in appropriate coordinates, the map becomes a family of translations on complex tori. Some natural generalizations of the pentagram map produce integrable systems, but numerical experiments by Khesin-Soloviev suggest that others do not. In this talk, we use tools from dynamical systems to prove that the “skew” pentagram map is non-integrable.

February 12, 2026
Analysis [5] Support of semiclassical measures in higher dimensions 4:00pm -
KT 201

A central question in quantum chaos is how classical chaotic dynamics influence quantum behavior. On compact Riemannian manifolds, pure quantum states correspond to Laplacian eigenfunctions. The quantum unique ergodicity (QUE) conjecture of Rudnick and Sarnak predicts that on hyperbolic manifolds, all high-energy eigenfunctions become uniformly distributed. The asymptotic behavior of eigenfunctions can be formulated in terms of semiclassical measures, which describe the microlocal distribution of eigenfunction mass. One approach towards the QUE conjecture applies microlocal analysis and uncertainty principles to characterize the support of semiclassical measures. I will discuss recent work that uses the breakthrough higher-dimensional fractal uncertainty principle of Cohen. Using this uncertainty principle, we prove the first result on the support of semiclassical measures on real hyperbolic n-manifolds. To explain some of the main proof ideas, we will discuss work on the toy model of quantum cat maps. This is joint work with Nicholas Miller.

Quantum Topology and Field Theory [6] Relationships between skein algebras 4:30pm -
KT 801

We will examine the multiplicative structure of two skein algebras—the usual Kauffman bracket skein algebra of a surface (generated by loops) and a generalization of it due to Roger-Yang (generated by loops and arcs).  In joint work with Chloe Marple, we found an unexpected homomorphism between the usual skein algebra for a closed torus and the Roger-Yang skein algebra for a twice-punctured annulus.  In this talk, I’ll discuss how we  used the homomorphism to help compute representations and structural constants of the Roger-Yang skein algebra for a twice-punctured annulus, and  whether there might be similar relationships between skein algebras for other surfaces. 

February 13, 2026
Learning seminar on Matroids and Algebraic Cycles [7] Learning seminar on Matroids and Algebraic Cycles 2:15pm -
KT 801

TBA

Learning seminar on Groups, Geometry and Dynamics [8] Coding of hyperbolic diffeomorphisms. 4:00pm -
KT 217

I’ll discuss how to leverage symbolic dynamics to understand Anosov diffeomorphisms of surfaces, starting with the most basic case of linear total automorphisms. The key idea is the construction of so-called Markov partitions that code the dynamics of the diffeomorphism. 

More recently, the same ideas have been extended to prove new results about general diffeomorphisms of manifolds. 

February 16, 2026
Geometric Analysis and Application [3] On Backwards uniqueness for singular mean curvature flows. 3:45pm -
KT 906

Mean curvature flow, the gradient flow of the area functional, is the most natural geometric heat flow for embedded hypersurfaces. Being non linear, the flow develops singularities, at which it stops being smooth. One fundamental, often delicate, question for such non linear flows is that of backwards uniqueness. In this talk I will discuss recent backwards uniqueness results, obtained jointly with Josh Daniels-Holgate, which can address some singularities. I will also compare these results to (commonly more robust) forward uniqueness results, and also to the situation in other equations.   

Geometry, Symmetry and Physics [4] Virtual Hodge numbers of the moduli space of maps to projective space 4:30pm -
KT 801

I will discuss joint work with Terry Song on the calculation of the virtual Hodge numbers (i.e. Hodge—Deligne polynomial, Hodge-Euler characteristic, etc.) of the moduli space of degree-d maps to projective space from smooth n-pointed curves of genus g. Up to Brill—Noether loci in genus g>= 3, I will show how to reduce the calculation to the corresponding invariants of M_g,n. This reduction implies a strong stability statement for the virtual Hodge numbers as functions of the degree d, and suggests homological stability properties of the moduli space generalizing known statements in genus zero.  As an intermediate result, I will outline an analogous calculation for the universal Jacobian over M_g,n. As I will discuss, the theory of symmetric functions is fundamental to our approach.

February 17, 2026
Geometry & Topology [11] Superrigidity of rich representations 4:30pm -
KT 207
In this talk, I will introduce the class of geodesically rich representations. These are representations of (real or complex) hyperbolic lattices that preserve a significant amount of the geometric structure of the associated quotient manifold. When the quotient manifold has robust geometric structure, these representations exhibit rigidity phenomena. In particular, a recent superrigidity theorem for rich representations was used to prove that finite-volume hyperbolic manifolds with infinitely many maximal totally geodesic submanifolds are arithmetic (Bader-Fisher-Miller-Stover). I will discuss a new superrigidity theorem for rich representations that efficiently recovers existing results and addresses target groups that were previously inaccessible.
February 19, 2026
Quantum Topology and Field Theory [6] Skeins, q-series, and modularity 4:30pm -
KT 801

Abstract:  I will describe a construction of a q-series invariant (BPS q-series, also known as the Z-hat invariant) associated to a 3-manifold decorated by an embedded link. These q-series depend only on the class of the link in the skein module, and hence define a homomorphism from the skein module to the space of q-series. The image of this homomorphism is conjectured to exhibit holomorphic quantum modularity, which suggests a new approach to Langlands duality for skein modules via q-series.

February 20, 2026
Learning seminar on Matroids and Algebraic Cycles [7] Learning seminar on Matroids and Algebraic Cycles 2:15pm -
KT 801

TBA

February 23, 2026
Geometric Analysis and Application [3] Splitting a manifold with (spectral) Ricci lower bounds 3:45pm -

In this talk, I will discuss the geometry of smooth complete manifolds where the first eigenvalue of the operator −γΔ + Ric, for γ > 0, is bounded from below. Here, Ric denotes the (pointwise) lowest eigenvalue of the Ricci tensor. This condition is weaker than a pointwise lower bound on Ricci curvature. In particular, I will focus on the following result. Let (Mⁿ,g) be a complete non-compact Riemannian manifold with at least two ends, and with n≥2. Assume u is a positive function on M satisfying −γΔu+Ric*u≥0 and γ<4/(n-1). Then, Mⁿ is isometric to the product of IR x Nⁿ⁻¹. This extends a result of Cheeger–Gromoll from 1971, and the bound required on γ is sharp. Joint work with M. Pozzetta and K. Xu.

https://yale.zoom.us/j/91979343134 [15]

February 24, 2026
Geometric Analysis Learning Seminar [9] Geometric Analysis Learning Seminar 10:30am -
KT 801

TBA

Geometry, Symmetry and Physics [4] Graded characters of Verma modules via the sphere trace 10:30am -
KT 329

I will talk about twisted traces on quantized Coulomb branches. Any Verma module over a quantized Coulomb branch gives rise to a twisted trace. For conical Coulomb branches there is also a trace introduced by Gaiotto and Okazaki (“sphere trace”). I will show how the sphere trace allows us to compute the graded character of Verma modules in certain cases. Based on joint work in progress with Vasily Krylov.

February 25, 2026
Group Actions and Dynamics [12] Random Walks on the Group of Planar Isometries and Local Limit Theorems 4:00pm -
KT205
We consider the fine-scale behavior of random walks on R^2 generated by successively applying independent random isometries to the origin.
We show that the walk equidistributes at a superpolynomial rate if the rotation parts satisfy a Diophantine condition,  and at a stretched exponential rate if the rotation parts are suitably algebraic. This extends results due to Varju and Lindenstrauss forisometries of R^3 to the more commutative and amenable setting of planar isometries. Based on joint work with Felipe Hernandez.
February 26, 2026
Analysis [5] Critical collapse in 2+1 gravity 4:00pm -
KT 201

Starting with the work of Choptuik ‘92, numerical relativity predicts that naked singularity spacetimes arise on the threshold of non-collapse and black hole formation, a phenomenon referred to as critical collapse. In this talk, I will present for 2+1 gravity the first rigorous construction of threshold naked singularities in general relativity. Joint work with Igor Rodnianski (Princeton University).

Quantum Topology and Field Theory [6] Finite N indices from branes and negative branes 4:30pm -
KT 801

Finite-N effects in large-N gauge theories, such as trace relations, are expected to be holographically dual to non-perturbative phenomena in string theory, such as Giant Graviton branes. A convenient setting to study these effects are supersymmetric indices of U(N) gauge theories. The finite-N indices can be reproduced by a series of corrections to the infinite-N result, known as the Giant Graviton expansion.

In this talk I will present a generalization of the Molien-Weyl formula computing generating functions of invariants of supergroups U(N|M), which arise as gauge groups of brane/negative brane systems in string theory. The formula leads to a new expansion relating finite-N and infinite-N indices of U(N) gauge theories. I will comment on its relation to Murthy’s Giant Graviton expansion and suggest a physical interpretation in terms of branes and negative branes. This talk is based on arXiv:2509.20451 and work in progress with Davide Gaiotto.

February 27, 2026
Learning seminar on Matroids and Algebraic Cycles [7] Learning seminar on Matroids and Algebraic Cycles 2:15pm -
KT 801

TBA

Learning seminar on Groups, Geometry and Dynamics [8] Learning seminar on Groups Geometry and Dynamics 4:00pm -
KT 801 or KT217

We will discuss the dynamics and ergodicity of Anosov diffeomorphisms and related systems.

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Links
[1] https://calendar.math.yale.edu/list/calendar/grid/week/2026-W05 [2] https://calendar.math.yale.edu/list/calendar/grid/week/2026-W07 [3] https://calendar.math.yale.edu/seminars/geometric-analysis-and-application [4] https://calendar.math.yale.edu/seminars/geometry-symmetry-and-physics [5] https://calendar.math.yale.edu/seminars/analysis [6] https://calendar.math.yale.edu/seminars/quantum-topology-and-field-theory [7] https://calendar.math.yale.edu/seminars/learning-seminar-matroids-and-algebraic-cycles [8] https://calendar.math.yale.edu/seminars/learning-seminar-groups-geometry-and-dynamics [9] https://calendar.math.yale.edu/seminars/geometric-analysis-learning-seminar [10] https://calendar.math.yale.edu/seminars/group-actions-geometry-and-dynamics [11] https://calendar.math.yale.edu/seminars/geometry-topology [12] https://calendar.math.yale.edu/seminars/group-actions-and-dynamics [13] https://calendar.math.yale.edu/list/calendar/grid/week/abstract/2026-W05 [14] https://calendar.math.yale.edu/list/calendar/grid/week/abstract/2026-W07 [15] https://yale.zoom.us/j/91979343134