BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CMSA - ECPv6.15.18//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:CMSA
X-ORIGINAL-URL:https://cmsa.fas.harvard.edu
X-WR-CALDESC:Events for CMSA
REFRESH-INTERVAL;VALUE=DURATION:PT1H
X-Robots-Tag:noindex
X-PUBLISHED-TTL:PT1H
BEGIN:VTIMEZONE
TZID:America/New_York
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20240310T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20241103T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20250309T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20251102T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20260308T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20261101T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20270314T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20271107T060000
END:STANDARD
END:VTIMEZONE
BEGIN:VTIMEZONE
TZID:America/New_York
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20240310T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20241103T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20250309T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20251102T060000
END:STANDARD
BEGIN:DAYLIGHT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
TZNAME:EDT
DTSTART:20260308T070000
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
TZNAME:EST
DTSTART:20261101T060000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251117T090000
DTEND;TZID=America/New_York:20251119T170000
DTSTAMP:20260503T191444
CREATED:20250502T182846Z
LAST-MODIFIED:20251215T145740Z
UID:10003749-1763370000-1763571600@cmsa.fas.harvard.edu
SUMMARY:Conference on Geometry and Statistics
DESCRIPTION:Conference on Geometry and Statistics \nDates: November 17–19\, 2025 \nLocation: CMSA G10\, 20 Garden Street\, Cambridge MA & via Zoom \n  \nSpeakers \n\nCharles Fefferman\, Princeton University\nStephan Huckemann\, Georg-August Universität Göttingen\nSungkyu Jung\, Seoul National University\nKei Kobayashi\, Keio University\nClément Levrard\, Université de Rennes\nKer-Chau Li\, University of California\, Los Angeles\nRong Ma\, Harvard University\nSteve Marron\, University of North Carolina\nEzra Miller\, Duke University\nHans-Georg Müller\, University of California\, Davis\nWilderich Tuschmann\, Karlsruhe Institute of Technology\nMelanie Weber\, Harvard University\nAndrew Wood\, Australian National University\nHorng-Tzer Yau\, Harvard University\n\nOrganizer: Zhigang Yao\, National University of Singapore \n  \nYoutube Playlist \n  \nSCHEDULE \ndownload pdf \nMonday\, Nov. 17\, 2025 \n9:00–9:25 am\nMorning refreshments \n9:25–9:30 am\nIntroductions \n9:30–10:30 am\nSpeaker: Stephan Huckemann\, Georg-August Universität Göttingen\nTitle: The Probability of the Cut Locus of a Fréchet Mean\nAbstract: We show that the cut locus of a Fréchet mean of a random variable on a connected and complete Riemanian manifold has zero probability\, a result known previously in special cases (Le and Barden\, 2014) and conjectured in general. The proof is based on first order and second order considerations\, where the latter are based on a recent result by Générau (2020) on “Laplacians in the barrier sense”. This generalizes to Fréchet p-means for p > 2. The former allow also to rule out stickiness on Riemannian manifolds\, and for generalization to 1 <= p < 2\, with a conjecture. We close with discussing and conjecturing extensions to noncomplete manifolds and more general metric spaces. This is joint work with Alexander Lytchak. \n\nGénérau\, F. (2020). Laplacian of the distance function on the cut locus on a Riemannian manifold. Nonlinearity 33(8)\, 3928.\nLe\, H. and D. Barden (2014).  On the measure of the cut locus of a Fréchet mean. Bulletin of the London Mathematical Society 46(4)\, 698–708.\nLytchak\, A. and S. F. Huckemann (2025). Zero mass at the cut locus of a Fréchet mean on a Riemannian manifold. arXiv preprint arXiv:2508.00747.\n\n10:30–10:45 am\nbreak \n10:45 am–11:45 am\nSpeaker: Hans-Georg Müller\, University of California\, Davis\nTitle: Conformal Inference for Random Objects\nAbstract: The underlying probability measure of random objects\, i.e.\, metric-space-valued random variables\, can be probed by distance profiles. These are one-dimensional distributions of probability mass falling into balls of increasing radius. In a regression setting with Euclidean covariates X and responses Y that are random objects\, one can consider conditional Fréchet means that can be implemented with Fréchet regression and also conditional distance profiles\, conditioning on X. Conditional distance profiles can then be leveraged to obtain conditional average transport costs\, the expected cost for transporting a fixed conditional distance profile to a randomly selected conditional distance profile. The conditional average transport costs can then be utilized to obtain conditional conformity scores. In conjunction with the split conformal algorithm these scores lead to conditional prediction sets located in the object space with asymptotic conditional validity and attractive finite sample behavior. Based on joint work Hang Zhou (UNC). \n11:45 am–1:15 pm\nLunch (Catered) \n1:15–2:15 pm\nSpeaker: Horng-Tzer Yau\, Harvard\nTitle: Ramanujan property of random regular graphs and delocalization of random band matrices\nAbstract: In this lecture\, we review recent works on random matrices. The first result is about the normalized adjacency matrix of a random $d$-regular graph on $N$ vertices with any fixed degree $d\geq 3$ and denote its eigenvalues as $\lambda_1=d/\sqrt{d-1}\geq \lambda_2\geq\lambda_3\cdots\geq \lambda_N$. We establish the edge universality for random $d$-regular graphs\, namely\, the distributions of $\lambda_2$ and $-\lambda_N$ converge to the Tracy-Widom$_1$ distribution associated with the Gaussian Orthogonal Ensemble. As a consequence\, for sufficiently large $N$\, approximately $69\%$ of $d$-regular graphs on $N$ vertices.\nare Ramanujan\, meaning $\max\{\lambda_2\,|\lambda_N|\}\leq 2$. This resolves a conjecture by Sarnak and Miller-Novikoff-Sabelli\nThe second result concerns $ N \times N$ Hermitian $d$-dimensional random band matrices with band width $W$. In the bulk of the spectrum and in the large $ N $ limit\, we prove that all $ L^2 $- normalized eigenvectors are delocalized in all dimensions under suitable conditions on $W$ and $N$. In addition\, we proved that the eigenvalue statistics are given by those of the Gaussian unitary ensemble. \n2:15–2:45 pm\nbreak with refreshments \n2:45–3:45 pm\nSpeaker: Clément Levrard\, Université de Rennes\nTitle: Optimal reach estimation\nAbstract: The reach of an embedded submanifold\, a notion that dates back to the famous work Curvature measures of H. Federer\, may be understood as a scale under which the submanifold is flat enough so that traditional Euclidean techniques in statistics locally apply\, up to some approximation. I will expose several ways to estimate the reach from sample (on the submanifold)\, some of them being optimal from the point of view of minimax estimation theory. Along the way\, intermediate estimation problems of local and global quantities will arise (curvature estimation\, weak feature size estimation\, distance estimation\, etc.)\, for which various phenomenons can occur from a statistical point of view (different convergence rates\, inconsistency). This will be an opportunity to provide a selective overview of the state of the art on these issues. \n4:30–5:30 pm\nCMSA Colloquium\nSpeaker: Zhigang Yao (National University of Singapore)\nTitle: Interaction of Statistics and Geometry: A New Landscape for Data Science\nAbstract:  Classical statistics views data as real numbers or vectors in Euclidean space\, but modern challenges increasingly involve data with intrinsic geometric structures. A central problem in this direction is manifold fitting\, with origins in H. Whitney’s work of the 1930s. The Geometric Whitney Problems ask: given a set\, when can we construct a smooth 𝑑-dimensional manifold that approximates it\, and how accurately can we estimate it?\nIn this talk\, I will discuss recent progress on manifold fitting and its role in bridging geometry and data science. While many existing methods rely on restrictive assumptions\, the manifold hypothesis—that data often lie near non-Euclidean structures—remains fundamental in modern statistical learning. I will highlight both theoretical insights and algorithmic challenges\, drawing on recent works with\, as well as ongoing research. \nYoutube video \n  \nTuesday\, Nov. 18\, 2025 \n9:00–9:30 am\nMorning refreshments \n9:30–10:30 am\nSpeaker: Charles Fefferman\, Princeton University (via Zoom)\nTitle: Extrinsic and intrinsic manifold learning\, old and new\nAbstract: The talk will include an exposition of the old paper “Testing the manifold hypothesis”\, joint work with S. Mitter and H. Narayanan\, on extrinsic manifold learning (the manifold to be learned is assumed to be embedded in a high-dimensional Euclidean space). The talk will also include a new result on intrinsic manifold learning (the manifold to be learned is not assumed to be embedded\, and the data consist of intrinsic distances corrupted by noise)\, provided the result is proven by the time of the conference. \n10:30–10:45 am\nbreak \n10:45 am–11:45 am\nSpeaker: Steve Marron\, University of North Carolina\nTitle: Data Integration Via Analysis of Manifolds (DIVAM)\nAbstract: A major challenge in the age of Big Data is the integration of disparate data types into a single data analysis. That was tackled by Data Integration Via Analysis of Subspaces (DIVAS) in the context of data blocks measured on a common set of experimental cases. Joint variation was defined in terms of modes of variation having identical scores across data blocks. DIVAS allowed mathematically rigorous formulation of individual variation within each data block in terms of individual modes. The goal of DIVAM is to intrinsically extend the DIVAS approach to data objects lying in manifolds\, such as shape data. \n11:45 am–1:15 pm\nLunch Break \n1:15–2:15 pm\nSpeaker: Ker-Chau Li\, University of California\, Los Angeles\nTitle: Investigation of Data clouds: From Galton’s Ellipses to Explainable AI (XAI)\, modeling or molding?\nAbstract: Francis Galton’s seminal 1886 visualization of regression toward the mean in trait inheritance is arguably the first and most influential example of geometric thinking applied to statistical modeling. The pioneering geometric insight driving Galton’s use of elliptical contours to discover the bivariate normal distribution laid down the foundation for classic multivariate analysis (e.g.\, PCA\, canonical correlation) and profoundly impacts modern methods like diffusion models.\nStatistical models\, particularly those based on parsimony\, are effective for characterizing data distribution and facilitating scientific rule induction. However\, the rise of unstructured big data (like images) has challenged these parsimonious approaches\, necessitating the use of deep learning models. These models\, containing billions of parameters\, sacrifice transparency to excel in prediction. Seeking solutions to this “black-box” dilemma is now the heart of Explainable AI (XAI).\nLeveraging the simplicity of elementary geometric concepts\, this talk will present a new path toward interpretable and parsimonious XAI. Unstructured big data is highly plastic. Our approach moves beyond the standard data modeling perspective—which answers what the data is—and introduces a novel data molding perspective. This shift is key to unlocking the full potential of data’s plasticity\, allowing us to effectively answer the crucial question: what the data can be used for.\nI will first discuss a connection between manifold learning and my earlier works\, helical confounding and liquid association. I will then turn to the data molding perspective and present two novel notions: mold-compliance and artificial-trait configurative-generation (ATCG). These notions guide our recent efforts in formulating novel algorithms for image data investigation\, addressing issues like prediction validity and within-class heterogeneity. Data molding entails a dramatically different feature space extraction\, which consequently shifts the subsequent investigation on the data clouds from out-of-distribution (OOD) to mold-violation\, and from UMAP clustering to ATCG-induced hierarchical clustering. \n2:15–2:45 pm\nbreak with refreshments \n2:45–3:45 pm\nSpeaker: Andrew Wood\, Australian National University\nTitle: Empirical likelihood methods for Fréchet means on open books\nAbstract: The open book is a simple example of a stratified space that captures some (but not all) of the properties of stratified spaces. Central limit theory for open books plus relevant background is given by Hotz et al. (2013\, Annals of Applied Probability). In this talk I will describe some basic inference procedures for Fréchet means in open books based on empirical likelihood (Owen\, book\, 2001). Empirical likelihood (EL) is a type of nonparametric likelihood that can be useful for many types of data\, including manifold-valued data and data from stratified spaces. An EL approach to basic inference for Fréchet means will be described. In particular\, it will be shown how the non-regularity in the geometry of open books can result in non-regular behaviour in Wilks’s theorem (i.e. the large sample likelihood ratio test). The talk will also discuss difficulties in extending the EL inference theory from open books to more general stratified spaces\, where the difference in dimension of adjacent strata can be 2 or more. For discussion of more general stratified spaces than open books\, see the orthant spaces discussed in Barden and Le (2018\, Proc of London Math Society) and the general stratified space setting considered by Mattingly et al. (2023\, arxiv). \n3:45–4:00 pm\nbreak \n4:00–5:00 pm\nSpeaker: Wilderich Tuschmann\, Karlsruhe Institute of Technology\nTitle: A Spectator’s Perspective on the Manifold Hypothesis\nAbstract: At its core\, the Manifold Hypothesis asserts that real-world\, high-dimensional data is not uniformly or randomly distributed throughout its high-dimensional “ambient” space\, but concentrated on or near a low-dimensional manifold (or a collection of manifolds) embedded within that high-dimensional ambient space.\nIn my talk\, I will discuss reasons and facts that speak for as well as against this hypothesis and also address geometric alternatives. \n  \nWednesday\, Nov. 19\, 2025 \n9:00–9:30 am\nMorning refreshments \n9:30–10:30 am\nSpeaker: Melanie Weber\, Harvard University\nTitle: Ricci Curvature\, Ricci Flow\, and the Geometry of Learning\nAbstract: Geometric structure in data plays a crucial role in machine learning. In this talk\, we study this observation through the lens of Ricci curvature and its associated Ricci flow. We start by reviewing a discrete notion of Ricci curvature introduced by Ollivier and the geometric flow that it induces. We further discuss the relationship between discrete Ricci curvature and its continuous counterpart via discrete-to-continuum consistency results\, which imply that discrete Ricci curvature can provably characterize the geometry of a data manifold based on a finite sample. This provides a theoretical foundation for several applications of discrete Ricci curvature in machine learning\, two of which we discuss in the remainder of this talk. First\, we analyze learned feature representations in deep neural networks and show that they transform during training in ways that closely resemble a discrete Ricci flow. Our analysis reveals that nonlinear activations shape class separability and suggests geometry-informed training principles such as early stopping and depth selection. Second\, we turn to deep learning on graphs\, where we address representational limitations of state of the art graph neural networks through curvature-based data augmentations. We show that augmenting input graphs with geometric information provably increases the representational power of such models and yields performance gains in practice. \n10:30–10:45 am\nbreak \n10:45 am–11:45 am\nSpeaker: Ezra Miller\, Duke University\nTitle: Extracting bar lengths from multiparameter persistent homology\nAbstract: Persistent homology in one parameter can be summarized using bar codes or persistence diagrams\, which are elementary gadgets with many features amenable to vectorization and hence statistical analysis. For example\, early work with Bendich\, Marron\, Pieloch\, and Skwerer showed how to extract meaningful statistics from the top 100 bar lengths in persistent homology summaries of brain arteries. The story for persistent homology with multiple parameters\, on the other hand\, is still developing. Although it has the potential to be much more flexible and informative\, multipersistence has structural issues that present fundamental mathematical challenges. There is no consensus on what might be meant by a “bar”\, let alone “the top 100 bar lengths”. This talk recalls the basics of single and multiparameter persistent homology and discusses some of the mathematical issues\, including obstacles and potential routes forward. \n11:45 am–1:15 pm\nLunch Break \n1:15–2:15 pm\nSpeaker: Kei Kobayashi\, Keio University\nTitle: Metric Transformations of Data Spaces: Curvature Control and Related Developments\nAbstract: We present our proposed method of increasing the accuracy of data analysis by means of two transformations of the metric of the data space. The first transformation is based on the curve length defined by the integral of the power of the density function\, which can be computed approximately using an empirical graph; the second transformation can be interpreted as the extrinsic distance when the data space is embedded in a metric cone. The advantage of both distance transformations is that the hyperparameters allow the curvature to be monotonically transformed in a specific sense. Some statistical applications of these transformations and theoretical justifications are presented. Detailed analyses of the geodesics obtained by this method for several simple probability distributions will also be presented. The main part of this work is based on joint works with Henry P. Wynn. \n2:15–2:45 pm\nbreak with refreshments \n2:45–3:45 pm\nSpeaker: Sungkyu Jung\, Seoul National University\nTitle: Generalized Frechet means with random minimizing domains and its strong consistency\nAbstract: In this talk\, I will discuss a novel extension of Frechet means\, referred to as generalized  Frechet  means\, as a comprehensive framework for describing the characteristics of random elements. The generalized Frechet mean is defined as the minimizer of a cost function\, and the framework encompasses various extensions of Frechet means that have appeared in the literature. The most distinctive feature of the proposed framework is that it allows the domain of minimization for the empirical generalized Frechet means to be random and different from that of its population counterpart. This flexibility broadens the applicability of the Frechet mean framework to various statistical scenarios\, including sequential dimension reduction for non-Euclidean data. We establish a strong consistency theorem for generalized Frechet means. Applications such as verifying the consistency of principal geodesic analysis on the hypersphere\, compositional principal component analysis on the composition space\, and k-medoids clustering for data on a metric space will be discussed. \n3:45–4:00 pm\nbreak \n4:00–5:00 pm\nSpeaker: Rong Ma\, Harvard University\nTitle: Modern Nonlinear Embedding Methods Unpacked\nAbstract: Learning and representing low-dimensional structures from noisy\, high-dimensional data is a cornerstone of modern data science. Stochastic neighbor embedding algorithms\, a family of nonlinear dimensionality reduction and data visualization methods\, with t-SNE and UMAP as two leading examples\, have become very popular in recent years. Yet despite their wide applications\, these methods remain subject to points of debate\, including limited theoretical understanding\, ambiguous interpretations\, and sensitivity to tuning parameters. In this talk\, I will present our recent efforts to decipher and improve these nonlinear embedding approaches. Our key results include a rigorous theoretical framework that uncovers the intrinsic mechanisms\, large-sample limits\, and fundamental principles underlying these algorithms; a set of theory-informed practical guidelines for their principled use in trustworthy biological discovery; and a collection of new algorithms that address current limitations and improve performance in areas such as bias reduction and stability. Throughout the talk\, I will highlight how these advances not only deepen our theoretical understanding but also open new avenues for scientific discovery.
URL:https://cmsa.fas.harvard.edu/event/geostat_2025/
LOCATION:CMSA 20 Garden Street Cambridge\, Massachusetts 02138 United States
CATEGORIES:Conference
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Geostat.3-scaled.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251117T150000
DTEND;TZID=America/New_York:20251117T160000
DTSTAMP:20260503T191444
CREATED:20251014T143757Z
LAST-MODIFIED:20251112T173007Z
UID:10003815-1763391600-1763395200@cmsa.fas.harvard.edu
SUMMARY:BV and the ThimTFT
DESCRIPTION:Quantum Field Theory and Physical Mathematics Seminar \nSpeaker: Justin Kulp\, Stony Brook \nTitle: BV and the ThimTFT \nAbstract: The SymTFT (or “quiche”) construction relates different global forms of d-dimensional QFTs with discrete symmetry: realizing different global forms as a (d+1)-dimensional TFT on an interval\, with a common “physical” boundary condition on one side\, and different topological boundary conditions on the other. In my talk\, I will describe an analogue of the SymTFT which relates theories with the same “perturbative equations of motion”\, but different non-perturbative completions.\nI will start with a lightning overview of conformal blocks and relative QFT\, then explain the BV formalism in some detail—focusing on the elegant (super)geometric story in 0d for simplicity. I will argue that there is a natural 1d cohomological TFT (called the ThimTFT) associated to the classical action S\, with different topological boundary conditions described by convergent path-integral contours in a complexified field space. Time permitting\, I will discuss extensions to higher dimensions. Based on WIP.
URL:https://cmsa.fas.harvard.edu/event/qft_111725/
LOCATION:CMSA Room G02\, 20 Garden Street\, Cambridge\, MA\, 02138
CATEGORIES:Quantum Field Theory and Physical Mathematics
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QFT-and-Physical-Mathematics-11.17.25.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251117T163000
DTEND;TZID=America/New_York:20251117T173000
DTSTAMP:20260503T191444
CREATED:20250925T180503Z
LAST-MODIFIED:20251106T161641Z
UID:10003799-1763397000-1763400600@cmsa.fas.harvard.edu
SUMMARY:Interaction of Statistics and Geometry: A New Landscape for Data Science
DESCRIPTION:Colloquium \nSpeaker: Zhigang Yao (National University of Singapore) \nTitle: Interaction of Statistics and Geometry: A New Landscape for Data Science \nAbstract:  Classical statistics views data as real numbers or vectors in Euclidean space\, but modern challenges increasingly involve data with intrinsic geometric structures. A central problem in this direction is manifold fitting\, with origins in H. Whitney’s work of the 1930s. The Geometric Whitney Problems ask: given a set\, when can we construct a smooth 𝑑-dimensional manifold that approximates it\, and how accurately can we estimate it? \nIn this talk\, I will discuss recent progress on manifold fitting and its role in bridging geometry and data science. While many existing methods rely on restrictive assumptions\, the manifold hypothesis—that data often lie near non-Euclidean structures—remains fundamental in modern statistical learning. I will highlight both theoretical insights and algorithmic challenges\, drawing on recent works with\, as well as ongoing research.
URL:https://cmsa.fas.harvard.edu/event/colloquium_111725/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-11.17.2025-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251120T140000
DTEND;TZID=America/New_York:20251120T150000
DTSTAMP:20260503T191444
CREATED:20251009T132440Z
LAST-MODIFIED:20251009T132850Z
UID:10003809-1763647200-1763650800@cmsa.fas.harvard.edu
SUMMARY:Differentials and Singularities
DESCRIPTION:Algebra Seminar \nSpeaker: Dawei Chen\, Boston College \nTitle: Differentials and Singularities \nAbstract: Given a holomorphic differential on a smooth algebraic curve\, we associate to it a Gorenstein curve singularity with Gm-action.  Conversely\, we show that every isolated Gorenstein curve singularity with Gm-action appears in this way.  This construction reveals a fascinating relation between differentials and singularities\, where the zero orders of the differentials determine the combinatorial data of the singularities.  In this talk\, I’ll provide many concrete examples of such singularities\, and explain how the study of deformations of these singularities can help us better understand the geometry of moduli spaces of differentials.  This is based on joint work with Fei Yu (Zhejiang University). \n 
URL:https://cmsa.fas.harvard.edu/event/algebra-seminar_112025/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebra Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Algebra-Seminar-11.19.25-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251120T160000
DTEND;TZID=America/New_York:20251120T170000
DTSTAMP:20260503T191444
CREATED:20250904T163048Z
LAST-MODIFIED:20251117T220513Z
UID:10003785-1763654400-1763658000@cmsa.fas.harvard.edu
SUMMARY:Tropical-Topological(Tropological) Sigma Models
DESCRIPTION:Differential Geometry and Physics Seminar  \nSpeaker: Andrés Franco Valiente\, UC Berkeley \nTitle: Tropical-Topological (Tropological) Sigma Models \nAbstract: Tropical geometry provides a powerful bridge between complex and combinatorial worlds\, allowing certain curve-counting invariants to be computed in a piecewise-linear “tropical” limit. Building on Mikhalkin’s insight that Gromov–Witten invariants can be recovered from tropical curves\, this talk revisits Mikhalkin’s result from the viewpoint of topological field theory and functional integration.  I will first review the topological sigma model and explain how the localization equations admit a natural notion of tropicalization which allows us to reproduce the Gromov-Witten invariants using standard cohomological BRST methods without having to reformulate the functional integral in terms of the tropical semifield. We find that the relevant geometries associated to the tropical limit of the topological sigma models no longer require a complex structure but they are instead based on nilpotent structures on singular foliated manifolds. We close with a discussion on recent progress on how the tropological sigma model has a close connection to Hořava’s topologicial quantum gravity for Ricci Flow in a joint work with Emil Albrychiewicz and Viola Zixin Zhao. \n  \n  \n 
URL:https://cmsa.fas.harvard.edu/event/dgphys_112025/
LOCATION:Virtual
CATEGORIES:Differential Geometry and Physics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/DG-Physics-Seminar-11.20.2025.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251121T120000
DTEND;TZID=America/New_York:20251121T130000
DTSTAMP:20260503T191444
CREATED:20250827T142348Z
LAST-MODIFIED:20251118T150222Z
UID:10003771-1763726400-1763730000@cmsa.fas.harvard.edu
SUMMARY:Optimal learning protocols via statistical physics and control theory
DESCRIPTION:Member Seminar \nSpeaker: Francesco Mori\, CMSA \nTitle: Optimal learning protocols via statistical physics and control theory \nAbstract: Behind the impressive performance of modern machine learning lies a toolkit of training tricks\, from tuning learning rates to curating training data. These heuristics are powerful but hard to interpret and possibly suboptimal\, leaving open the challenge of finding general principles for protocol design. In this talk\, I will present a framework that combines tools from statistical physics and control theory to identify optimal training strategies in simple yet insightful neural network models. In the high-dimensional limit\, the training dynamics can be reduced to closed-form ordinary differential equations for a small set of order parameters that track learning. This reduction allows us to pose the design of training protocols as an optimal control problem directly on the order-parameter dynamics\, with the objective of minimizing the generalization error. This formulation encompasses a variety of learning scenarios and yields principled training strategies that clarify\, and in some cases improve upon\, standard heuristic practices.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-112125/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Member-Seminar-11.21.25.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251124T163000
DTEND;TZID=America/New_York:20251124T173000
DTSTAMP:20260503T191444
CREATED:20251119T163856Z
LAST-MODIFIED:20251119T184001Z
UID:10003834-1764001800-1764005400@cmsa.fas.harvard.edu
SUMMARY:Geometric Simplicity in Quantum Field Theory and Gravity
DESCRIPTION:Colloquium \nSpeaker: Thomas Grimm\, Utrecht University \nTitle: Geometric Simplicity in Quantum Field Theory and Gravity \nAbstract: In physics we attribute much value to the emergence of simplicity\, both conceptually and for computations. Familiar examples include algebraic relations among Feynman amplitudes\, the surprising descriptions arising in large-N or duality limits\, and the central role played by symmetries. In this colloquium we discuss how tame geometry allows one to quantitatively describe such simplifications by introducing a measure of complexity. This framework relies on finiteness: the information content of the functions and domains required to specify a theory\, or an observable is finite. A key strength of the proposal is its generality as it applies to any physical quantity and can therefore be used both to analyze complexities within an individual Quantum Field Theory and to study the entire space of such theories. We present several applications and explain how this perspective ties in with our understanding of the expected properties of effective theories that can be coupled to Quantum Gravity.
URL:https://cmsa.fas.harvard.edu/event/colloquium-112425/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-11.24.2025.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251125T161500
DTEND;TZID=America/New_York:20251125T183000
DTSTAMP:20260503T191444
CREATED:20251021T202057Z
LAST-MODIFIED:20251124T145931Z
UID:10003821-1764087300-1764095400@cmsa.fas.harvard.edu
SUMMARY:Coulomb branches and KLRW algebras
DESCRIPTION:Geometry and Quantum Theory Seminar \nSpeaker:Vasily Krylov\, CMSA \nTitle: Coulomb branches and KLRW algebras \nAbstract: I will introduce Coulomb branches associated to a pair of a reductive group G and its complex representation N. We will discuss their main geometric properties and examine explicit examples. I will also highlight the connection to the moduli space of monopoles. Time permitting\, we will see how KLRW naturally arise in this context.
URL:https://cmsa.fas.harvard.edu/event/quantumgeo_112525/
LOCATION:Science Center 507\, 1 Oxford Street\, Cambridge\, 02138
CATEGORIES:Geometry and Quantum Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Geometry-Quantum-Theory-11.25.25-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251201T163000
DTEND;TZID=America/New_York:20251201T173000
DTSTAMP:20260503T191444
CREATED:20251007T152747Z
LAST-MODIFIED:20251201T144411Z
UID:10003807-1764606600-1764610200@cmsa.fas.harvard.edu
SUMMARY:Asymptotic Theory of Attention: In-Context Learning and Sparse Token Detection
DESCRIPTION:Colloquium \nSpeaker: Yue M. Lu\, Harvard University \nTitle: Asymptotic Theory of Attention: In-Context Learning and Sparse Token Detection \nAbstract: Attention-based architectures exhibit striking emergent abilities—from learning tasks directly from context to detecting rare\, weak features in long sequences—yet a rigorous theory explaining these behaviors remains limited. In this talk\, I will present two recent exactly solvable models that develop a high-dimensional asymptotic theory of attention. \n(i) In-context learning. For linear attention pretrained on linear regression tasks\, we derive sharp asymptotics in a regime where token dimension\, context length\, and task diversity all scale proportionally\, while the number of pretraining examples scales quadratically. The resulting learning curve exhibits double descent and a phase transition separating a low-diversity memorization regime from a high-diversity regime of genuine in-context generalization. These predictions closely track empirical behavior in both linear-attention models and nonlinear Transformer architectures. \n(ii) Sparse-token classification. For detecting weak signals embedded in a small\, randomly located subset of tokens\, we analyze a single-layer attention classifier and determine its representational and learnability thresholds. Attention succeeds with only logarithmic signal scaling in the sequence length L\, outperforming linear baselines that require √L scaling. In a proportional high-dimensional regime\, we prove that two gradient descent steps yield nontrivial alignment between the query vector and the hidden signal\, leading to signal-adaptive attention. Exact formulas for the test error\, training loss\, and separability capacity quantify this advantage.
URL:https://cmsa.fas.harvard.edu/event/colloquium-12125/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-12.1.2025-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251202T161500
DTEND;TZID=America/New_York:20251202T183000
DTSTAMP:20260503T191444
CREATED:20251021T202125Z
LAST-MODIFIED:20251201T192115Z
UID:10003822-1764692100-1764700200@cmsa.fas.harvard.edu
SUMMARY:Homological mirror symmetry for Coulomb branches
DESCRIPTION:Geometry and Quantum Theory Seminar \nSpeaker: Sebastian Haney\, Harvard \nTitle: Homological mirror symmetry for Coulomb branches \nAbstract: I will describe a result of Aganagic\, Danilenko\, Li\, Shende\, and Zhou which constructs a embeddings of certain cylindrical KLRW categories into Fukaya-Seidel categories of multiplicative Coulomb branches. This can be thought of as a homological mirror symmetry statement relating the Fukaya category of a multiplicative Coulomb branch to the derived category of a resolved additive Coulomb branch. I will describe the construction of the relevant Fukaya–Seidel categories\, and explain how the KRLW relations are realized by counts of holomorphic disks in symmetric products of surfaces. \n\n 
URL:https://cmsa.fas.harvard.edu/event/quantumgeo_12225/
LOCATION:Science Center 507\, 1 Oxford Street\, Cambridge\, 02138
CATEGORIES:Geometry and Quantum Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Geometry-Quantum-Theory-12.2.25-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251203T140000
DTEND;TZID=America/New_York:20251203T150000
DTSTAMP:20260503T191444
CREATED:20251110T191407Z
LAST-MODIFIED:20251110T225824Z
UID:10003833-1764770400-1764774000@cmsa.fas.harvard.edu
SUMMARY:Machine learning tools for mathematical discovery
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Adam Zsolt Wagner\, Google DeepMind \nTitle: Machine learning tools for mathematical discovery \nAbstract: I will discuss various ML tools we can use today to try to find interesting constructions to various mathematical problems. I will briefly mention simple reinforcement learning setups and PatternBoost\, but the talk will mainly focus on LLM-based tools such as FunSearch and AlphaEvolve. We will discuss the pros and cons of several of these methods\, and try to figure out which one is best for the problems we care about.\nJoint work with François Charton\, Jordan Ellenberg\, Bogdan Georgiev\, Javier Gómez-Serrano\, Terence Tao\, and Geordie Williamson.
URL:https://cmsa.fas.harvard.edu/event/newtech_12325/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-12.3.2025-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251203T170000
DTEND;TZID=America/New_York:20251203T180000
DTSTAMP:20260503T191444
CREATED:20250409T160258Z
LAST-MODIFIED:20251205T171720Z
UID:10003659-1764781200-1764784800@cmsa.fas.harvard.edu
SUMMARY:Millennium Prize Problems Lecture - Madhu Sudan: P vs NP Problem
DESCRIPTION:Pamphlet (pdf) \nSlides (pdf) \nDate: December 3\, 2025 \nTime: 5:00–6:00 pm \nLocation: Harvard Science Center Hall D\, 1 Oxford St.\, Cambridge MA \nSpeaker: Madhu Sudan\, Harvard University \nTitle: The P vs. NP problem: An Existential Question for Mathematics \nAt the beginning of the twentieth century\, in response to questions raised by Hilbert\, illustrious mathematicians such as Godel\, Church and Turing formalized the notion of theorems and proofs. Proofs were automatically verifiable while theorems are logical propositions for which proofs exist. The formal definition of a computer\, a definition that had strong influence on the later development of the technology\, was a by-product of the effort to define the phrase “automatically verifiable”! \nWhile the resulting theory had major implications already\, one notion was however missing in the early definitions. Proofs were meant to be easily verifiable\, while determining the truth of a proposition/conjecture (arguably a core task of mathematics) was not necessarily so. But what is “easiness” and how is it to be defined? While this was already hinted at by Godel in the 50s\, the notion was finally formalized in seminal works of Cook\, Levin and Karp in the early 70s. Central notions here included the adoption of the notion that polynomial time algorithms are (the only) tractable ones\, and the realization that algorithms seeking to remove the existential quantifier in the definition of a “theorem” lead naively to exponential time algorithms. But are there no sophisticated algorithms to search for proofs? This is the profound “Is P = NP?” question. \nIn this talk we will introduce the question and explain implications of resolutions of this question to the modern computing infrastructure\, to mathematics and other sciences. We will briefly describe the state of progress on this question and recent progress on weaker forms of this question. Finally we will also aim to connect this question\, and why one may believe that P != NP (proof search can not be automated) even in the face of accumulating evidence on the ability of computers to solve more and more complex mathematical problems\, which seem to implement brute force search in less than polynomial time. \n  \nRead more about the P vs NP Problem at the Clay Math website. \n  \nOrganizers: Martin Bridson\, Clay Mathematics Institute | Dan Freed\, Harvard University and CMSA | Mike Hopkins\, Harvard University \n\n                   \n\nMillennium Prize Problems Lecture Series
URL:https://cmsa.fas.harvard.edu/event/clay_12325/
LOCATION:Harvard Science Center Hall D\, 1 Oxford Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Millennium Prize Problems Lecture,Special Lectures
ATTACH;FMTTYPE=image/jpeg:https://cmsa.fas.harvard.edu/media/Sudan_web-ad_CROP-scaled.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251204T120000
DTEND;TZID=America/New_York:20251204T130000
DTSTAMP:20260503T191444
CREATED:20250904T163130Z
LAST-MODIFIED:20251203T150446Z
UID:10003786-1764849600-1764853200@cmsa.fas.harvard.edu
SUMMARY:Towards a Dolbeault AGT correspondence
DESCRIPTION:Differential Geometry and Physics Seminar  \nSpeaker: Surya Raghavendran\, Yale \nTitle: Towards a Dolbeault AGT correspondence \nAbstract: The AGT correspondence and its extensions propose geometric constructions of vertex algebras and their modules from the cohomology of various moduli spaces of sheaves on surfaces. Physically\, the correspondence is illuminated throgh the holomorphic–topological twist of the six-dimensional N=(2\,0) superconformal field theories. In this talk\, I will describe a variant of AGT arising instead from the so-called minimal twist of these theories. In this setting\, the natural algebraic structures are holomorphic factorization algebras in three complex dimensions. From these\, one can extract an associative algebra together with a natural module\, which we conjecture to coincide with a quantization of the moduli of Higgs sheaves on surfaces. In examples\, this pair is furthermore expected to admit a Hodge–de Rham deformation to the Heisenberg algebra and its action on the cohomology of Hilbert schemes of surfaces\, as constructed by Grojnowski and Nakajima. \n  \n  \n 
URL:https://cmsa.fas.harvard.edu/event/dgphys_12425/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Differential Geometry and Physics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/DG-Physics-Seminar-12.4.2025.docx-1-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251205T120000
DTEND;TZID=America/New_York:20251205T130000
DTSTAMP:20260503T191444
CREATED:20250827T142953Z
LAST-MODIFIED:20251202T160532Z
UID:10003772-1764936000-1764939600@cmsa.fas.harvard.edu
SUMMARY:A combinatorial formula for interpolation Macdonald polynomials
DESCRIPTION:Member Seminar \nSpeaker: Houcine Ben Dali\, Harvard CMSA \nTitle: A combinatorial formula for interpolation Macdonald polynomials \nAbstract: In 1996\, Knop and Sahi introduced a remarkable family of inhomogeneous symmetric polynomials\, defined via vanishing conditions\, whose top homogeneous parts are exactly the Macdonald polynomials. Like the Macdonald polynomials\, these interpolation Macdonald polynomials are closely connected to the Hecke algebra\, and admit nonsymmetric versions\, which generalize the nonsymmetric Macdonald polynomials. I will present a combinatorial formula for interpolation Macdonald polynomials in terms of signed multiline queues. This formula generalizes the combinatorial formula for Macdonald polynomials in terms of multiline queues given by Corteel–Mandelshtam–Williams. This is based on a joint work with Lauren Williams.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-12525/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Member-Seminar-12.5.25.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251208T150000
DTEND;TZID=America/New_York:20251208T160000
DTSTAMP:20260503T191444
CREATED:20251202T152832Z
LAST-MODIFIED:20251202T160431Z
UID:10003841-1765206000-1765209600@cmsa.fas.harvard.edu
SUMMARY:Computing WKB periods 
DESCRIPTION:Quantum Field Theory and Physical Mathematics Seminar \nSpeaker: Max Meynig\, University of Connecticut \nTitle: Computing WKB periods \nAbstract:  In one dimensional quantum mechanics\, the all-orders WKB method leads to ‘quantum periods’ which are formal power series in \hbar whose coefficients are certain period integrals. These periods\, which limelight in supersymmetric/string theories\, have rich structure and can be computed in a number of ways. I will discuss a new perspective on them and their computation.
URL:https://cmsa.fas.harvard.edu/event/qft_12825/
LOCATION:CMSA Room G02\, 20 Garden Street\, Cambridge\, MA\, 02138
CATEGORIES:Quantum Field Theory and Physical Mathematics
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QFT-and-Physical-Mathematics-12.8.25.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251208T163000
DTEND;TZID=America/New_York:20251208T173000
DTSTAMP:20260503T191444
CREATED:20251202T153625Z
LAST-MODIFIED:20251202T162404Z
UID:10003843-1765211400-1765215000@cmsa.fas.harvard.edu
SUMMARY:Recent Advances in Probabilistically Checkable Proofs
DESCRIPTION:Colloquium \nSpeaker: Dor Minzer (MIT) \nTitle: Recent Advances in Probabilistically Checkable Proofs \nAbstract: The PCP Theorem is a cornerstone of computer science\, with applications to hardness of approximation\, verification\, interactive protocols and more. It asserts a witness for the satisfiability of a given 3CNF formula can be encoded in a robust way that allows local checking.In this talk we discuss recent developments in PCPs\, and their connection with distributed protocols\, high-dimensional expanders and discrete Fourier analysis. Based on joint works with Kai Zhe Zheng\, Mitali Bafna\, Noam Lifshitz\, Nikhil Vyas.
URL:https://cmsa.fas.harvard.edu/event/colloquium-12825/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-12.8.2025.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251209T161500
DTEND;TZID=America/New_York:20251209T183000
DTSTAMP:20260503T191444
CREATED:20251031T145823Z
LAST-MODIFIED:20251208T150959Z
UID:10003830-1765296900-1765305000@cmsa.fas.harvard.edu
SUMMARY:Geometry and Quantum Theory Seminar
DESCRIPTION:Geometry and Quantum Theory Seminar \nSpeaker: Lorenzo Riva\, CMSA \nTitle: Aganagic’s invariant is Khovanov homology \nAbstract: Webster computed the Khovanov homology of (the closure of) a braid in terms of the action of that braid on a certain KLRW category. Aganagic proposed that the same computation could be done in the Fukaya-Seidel category of the multiplicative Coulomb branch associated to a weighted quiver. In this talk we will recap the story so far and then sketch LePage and Shende’s proof of Aganagic’s proposal. \n  \nSpeaker: Bowen Yang\, CMSA \nTitle: Some groups from Condensed matter physics \nAbstract: I would like to talk about some groups coming from the study of quantum spin systems. They inspired a construction of generalized homology theories related to Azumaya algebras. \n  \n  \n 
URL:https://cmsa.fas.harvard.edu/event/quantumgeo_12925/
LOCATION:Science Center 507\, 1 Oxford Street\, Cambridge\, 02138
CATEGORIES:Geometry and Quantum Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Geometry-Quantum-Theory-12.9.25-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251210T120000
DTEND;TZID=America/New_York:20251210T130000
DTSTAMP:20260503T191444
CREATED:20251209T223200Z
LAST-MODIFIED:20251209T223544Z
UID:10003844-1765368000-1765371600@cmsa.fas.harvard.edu
SUMMARY:CMSA Q&A Seminar: Dan Freed\, CMSA
DESCRIPTION:CMSA Q&A Seminar \nSpeaker: Dan Freed\, CMSA \nTopic: Constructions of homotopy types in geometry and physics \n 
URL:https://cmsa.fas.harvard.edu/event/cmsaqa_121025/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:CMSA Q&A Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Q-A-Seminar-12.10.2025-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251211T140000
DTEND;TZID=America/New_York:20251211T150000
DTSTAMP:20260503T191444
CREATED:20251202T153632Z
LAST-MODIFIED:20251202T161106Z
UID:10003842-1765461600-1765465200@cmsa.fas.harvard.edu
SUMMARY:Covers of curves\, Ceresa cycles\, and unlikely intersections
DESCRIPTION:Algebra Seminar \nSpeaker: Padamavathi Srinivasan\, Boston University \nTitle: Covers of curves\, Ceresa cycles\, and unlikely intersections \nAbstract: The Ceresa cycle is a canonical homologically trivial algebraic cycle associated to a curve in its Jacobian. In his 1983 thesis\, Ceresa showed that this cycle is algebraically nontrivial for a very general complex curve of genus at least 3. In the last few years\, there have been many new results shedding light on the locus in the moduli space of genus g curves where the Ceresa cycle becomes torsion. We will survey these recent results and provide new examples of positive dimensional families of curves where only finitely many members of the family have torsion Ceresa cycle. The main idea is to study covers of curves with many automorphisms\, and we will explain how we use the covering maps together with results on unlikely intersections in abelian varieties to construct such families. This is joint work with Tejasi Bhatnagar\, Sheela Devadas and Toren D’Nelly Warady. \n 
URL:https://cmsa.fas.harvard.edu/event/algebra-seminar_121125/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebra Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Algebra-Seminar-12.11.25.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251215T163000
DTEND;TZID=America/New_York:20251215T173000
DTSTAMP:20260503T191444
CREATED:20251124T150428Z
LAST-MODIFIED:20251211T145044Z
UID:10003836-1765816200-1765819800@cmsa.fas.harvard.edu
SUMMARY:The active Young-Dupré equation
DESCRIPTION:Colloquium \nSpeaker: Julien Tailleur\, MIT \nTitle: The active Young-Dupré equation \nAbstract: The Young-Dupré equation is a cornerstone of the equilibrium theory of capillary and wetting phenomena. In the biological world\, interfacial phenomena are ubiquitous\, from the spreading of bacterial colonies to tissue growth and flocking of birds\, but the description of such active systems escapes the realm of equilibrium physics. I will show how a microscopic\, mechanical definition of surface tension allows building an Active Young-Dupré equation able to account for the partial wetting observed in simulations of active particles interacting via pairwise forces. Remarkably\, the equation shows that the corresponding steady interfaces do not result from a simple balance between the surface tensions at play but instead emerge from a complex feedback mechanism. The interfaces are indeed stabilized by a drag force due to the emergence of steady currents\, which are themselves a by-product of the symmetry breaking induced by the interfaces. These currents also lead to new physics by selecting the sizes and shapes of adsorbed droplets\, breaking the equilibrium scale-free nature of the problem. Finally\, I will demonstrate a spectacular consequence of the negative value of the liquid-gas surface tensions in systems undergoing motility-induced phase separation: partially-immersed objects are expelled from the liquid phase\, in stark contrast with what is observed in passive systems. These results lay the foundations for a theory of wetting in active systems.
URL:https://cmsa.fas.harvard.edu/event/colloquium-121525/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-12.15.2025.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251216T140000
DTEND;TZID=America/New_York:20251216T150000
DTSTAMP:20260503T191444
CREATED:20251210T174651Z
LAST-MODIFIED:20251211T144851Z
UID:10003845-1765893600-1765897200@cmsa.fas.harvard.edu
SUMMARY:Electrical networks\, Grassmannians\, and cluster algebras
DESCRIPTION:Algebra Seminar \nSpeaker: Lazar Guterman\, Hebrew University of Jerusalem \nTitle: Electrical networks\, Grassmannians\, and cluster algebras \nAbstract: An electrical network with $n$ boundary vertices induces a matrix called the response matrix which measures the electrical properties of the network. The set of response matrices of all electrical networks has a characterization in terms of positivity of circular minors. Alman\, Lian and Tran constructed a cluster algebra on the set of circular minors\, which encodes the tests for positivity of these minors. Lam established the embedding of the set of electrical networks with $n$ boundary vertices into the totally nonnegative Grassmannian $Gr_{\ge0}(n-1\,2n)$. The coordinate ring of the Grassmannian has a cluster algebra structure as was proved by Scott. Given an electrical network\, we find a relation between circular minors of its response matrix and Plücker coordinates of its image in the Grassmannian. Using this property\, we prove that for an odd $n$ the two cluster algebras\, on circular minors and on the Grassmanian\, become isomorphic after a natural freezing and subsequent trivialization of certain variables in their initial seeds. We apply this isomorphism in order to relate the tests for positivity of circular minors to tests for positivity in the Grassmannian. The talk is based on a joint work with Boris Bychkov and Anton Kazakov. \n 
URL:https://cmsa.fas.harvard.edu/event/algebra-seminar_121625/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebra Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Algebra-Seminar-12.16.25.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20251216T161500
DTEND;TZID=America/New_York:20251216T183000
DTSTAMP:20260503T191444
CREATED:20251031T150328Z
LAST-MODIFIED:20251031T150328Z
UID:10003824-1765901700-1765909800@cmsa.fas.harvard.edu
SUMMARY:Geometry and Quantum Theory Seminar
DESCRIPTION:Geometry and Quantum Theory Seminar \nSpeaker: tba
URL:https://cmsa.fas.harvard.edu/event/quantumgeo_121625/
LOCATION:Science Center 507\, 1 Oxford Street\, Cambridge\, 02138
CATEGORIES:Geometry and Quantum Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260127T161500
DTEND;TZID=America/New_York:20260127T183000
DTSTAMP:20260503T191444
CREATED:20250407T174204Z
LAST-MODIFIED:20260126T163039Z
UID:10003739-1769530500-1769538600@cmsa.fas.harvard.edu
SUMMARY:The Quasi-Adiabatic Theorem and All That
DESCRIPTION:Geometry and Quantum Theory Seminar \nSpeaker: Daniel Spiegel\, Harvard \nTitle: The Quasi-Adiabatic Theorem and All That \nAbstract: Yosuke Kubota has recently made progress on understanding Kitaev’s conjecture by constructing a loop spectrum consisting of spaces of quantum spin systems\, indexed by spatial dimension of the lattice (arXiv: 2503.12618). After a brief reminder on the C*-algebraic formalism of quantum spin systems\, I will discuss Section 2 of this paper\, which covers some of the more analytical tools used to construct the loop spectrum. In particular\, I will focus on the quasi-adiabatic theorem which roughly speaking states that a smooth path of gapped Hamiltonians with unique ground states gives rise to a path of nice automorphisms that map the ground state at time zero to the path of ground states.
URL:https://cmsa.fas.harvard.edu/event/quantumgeo_12726/
LOCATION:Science Center 507\, 1 Oxford Street\, Cambridge\, 02138
CATEGORIES:Geometry and Quantum Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Geometry-Quantum-Theory-1.27.26-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260128T160000
DTEND;TZID=America/New_York:20260128T173000
DTSTAMP:20260503T191444
CREATED:20260116T182955Z
LAST-MODIFIED:20260116T182955Z
UID:10003871-1769616000-1769621400@cmsa.fas.harvard.edu
SUMMARY:CMSA Spring Welcome Back Event
DESCRIPTION:CMSA Spring Welcome Back Event \nDate: Jan 28\, 2026 \nTime: 4:00 pm \nLocation: CMSA Common Room\, 20 Garden Street\, Cambridge MA \nAll CMSA and Math affiliates are invited.
URL:https://cmsa.fas.harvard.edu/event/welcome126/
LOCATION:20 Garden Street\, Cambridge\, MA 02138\, MA\, MA\, 02138\, United States
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260129T133000
DTEND;TZID=America/New_York:20260129T143000
DTSTAMP:20260503T191444
CREATED:20251223T195721Z
LAST-MODIFIED:20260122T171100Z
UID:10003860-1769693400-1769697000@cmsa.fas.harvard.edu
SUMMARY:Complete Calabi-Yau Metrics and Optimal Transport
DESCRIPTION:Differential Geometry and Physics Seminar \nSpeaker: Tristan Collins\, University of Toronto \nTitle: Complete Calabi-Yau Metrics and Optimal Transport \nAbstract: I will discuss the connection between optimal transport and the existence of complete Calabi-Yau metrics on log Calabi-Yau varieties.  I will explain how the geometric problem of constructing complete Calabi-Yau metrics gives rise to problems in the boundary regularity theory for optimal transport\, and how ideas from geometry can be used to make progress on some of these problems.  This talk will survey joint works with Li\, Tong\, Tong-Yau\, Firester\, and Tong-Firester.
URL:https://cmsa.fas.harvard.edu/event/dgphys_12926/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Differential Geometry and Physics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/DG-Physics-Seminar-1.29.26-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260129T160000
DTEND;TZID=America/New_York:20260129T170000
DTSTAMP:20260503T191444
CREATED:20250911T184647Z
LAST-MODIFIED:20251223T202516Z
UID:10003792-1769702400-1769706000@cmsa.fas.harvard.edu
SUMMARY:Algebra Seminar
DESCRIPTION:Algebra Seminar \n 
URL:https://cmsa.fas.harvard.edu/event/algebra-seminar_12926/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebra Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260130T120000
DTEND;TZID=America/New_York:20260130T130000
DTSTAMP:20260503T191444
CREATED:20251014T142709Z
LAST-MODIFIED:20260128T171404Z
UID:10003811-1769774400-1769778000@cmsa.fas.harvard.edu
SUMMARY:Some results about saturation
DESCRIPTION:Member Seminar \nSpeaker: Stephen Landsittel \nTitle: Some results about saturation \nAbstract: Given a local ring R we can ask when saturation of ideals in R commutes with other operations on ideals (such as extension to a ring containing R). We show that the condition that extension of ideals along a ring map R \to S commutes with saturation controls inherent properties of the rings R & S\, such as Cohen-Macaulayness and unramifiedness.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-13026/
LOCATION:Common Room\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Member-Seminar-1.30.26.docx-1-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260130T133000
DTEND;TZID=America/New_York:20260130T163000
DTSTAMP:20260503T191444
CREATED:20260108T211634Z
LAST-MODIFIED:20260122T164709Z
UID:10003870-1769779800-1769790600@cmsa.fas.harvard.edu
SUMMARY:Freedman Seminar: Michael Freedman\, CMSA & Slava Krushkal\, University of Virginia
DESCRIPTION:Freedman Seminar \nSpeakers: Michael Freedman\, CMSA and Slava Krushkal\, University of Virginia (2-3 pm and 3:15-4:15 pm) \nTitle: Formulating 4D surgery for AI agents \nAbstract: The topological category surgery exact sequence is still open for free groups (and most groups of exponential growth). The lack of knowledge is about both surgery and s-cobordism; and the source of the mystery is the same in both cases. Thinking about how to present this problem to AIs has had its own value. In a pair of talks we will explain how we have thought about the problem in the past and how we are thinking about it now.
URL:https://cmsa.fas.harvard.edu/event/freedman_13026/
LOCATION:Hybrid
CATEGORIES:Freedman Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Freedman-Seminar-1.30.26-1-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260202T150000
DTEND;TZID=America/New_York:20260202T160000
DTSTAMP:20260503T191444
CREATED:20251223T185600Z
LAST-MODIFIED:20260126T185935Z
UID:10003816-1770044400-1770048000@cmsa.fas.harvard.edu
SUMMARY:Reflexive Polytopes and the Convergence of Feynman Integrals
DESCRIPTION:Quantum Field Theory and Physical Mathematics Seminar \nSpeaker: Pierre Vanhove (Institute of Theoretical Physics – Saclay) \nTitle: Reflexive Polytopes and the Convergence of Feynman Integrals \nAbstract: In the parametric representation\, Feynman integrals can be viewed as Euler integrals defined by the Symanzik polynomials of a graph. The convergence properties of these integrals are intimately tied to the combinatorial geometry of their associated Newton polytopes; specifically\, finiteness is guaranteed when the polytope contains interior points. We present a classification of Feynman integrals associated with polytopes containing a unique interior point\, identifying a subset that are reflexive. Our results show that such reflexive polytopes are surprisingly scarce within the space of Feynman graphs. We conclude by computing several infinite families of these integrals and exploring their connections to mirror symmetry and toric geometry. This is based on joint work with Leonardo de la Cruz and Pavel Novichkov.
URL:https://cmsa.fas.harvard.edu/event/qft_2226/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Field Theory and Physical Mathematics
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-QFT-and-Physical-Mathematics-2.2.26-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260202T163000
DTEND;TZID=America/New_York:20260202T173000
DTSTAMP:20260503T191444
CREATED:20251223T190540Z
LAST-MODIFIED:20260122T163725Z
UID:10003849-1770049800-1770053400@cmsa.fas.harvard.edu
SUMMARY:Bijections for hyperplane arrangements of Coxeter type
DESCRIPTION:Colloquium \nSpeaker: Olivier Bernardi\, Brandeis University \nTitle: Bijections for hyperplane arrangements of Coxeter type \nAbstract: This talk is about real hyperplane arrangements whose hyperplanes are of the form {xi −xj = s} or {xi +xj = s}. We describe a bijective framework for a large family of such arrangements which we call transitive. For each transitive arrangement A\, we give a bijection between the regions of A and a set of decorated trees. Particular cases include the families of Catalan\, Shi\, semiorder and Linial arrangements in type A\, B\, C\, D and BC. We also derive some general enumerative formulas for such families of transitive arrangements.
URL:https://cmsa.fas.harvard.edu/event/colloquium-2226/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-2.2.2026.docx-scaled.png
END:VEVENT
END:VCALENDAR