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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260424T120000
DTEND;TZID=America/New_York:20260424T130000
DTSTAMP:20260430T225525
CREATED:20260212T190445Z
LAST-MODIFIED:20260420T151342Z
UID:10003907-1777032000-1777035600@cmsa.fas.harvard.edu
SUMMARY:The Intermingling of Symmetry and Parametrization in Matrix Product States
DESCRIPTION:Member Seminar \nSpeaker: Daniel Spiegel \nTitle: The Intermingling of Symmetry and Parametrization in Matrix Product States \nAbstract: In the study of quantum spin systems\, it is by now well-known that interesting phases of quantum matter can arise from gapped ground states when the system is invariant under a symmetry group G or when the system varies continuously with a parameter in a topological space X. In these cases\, phases are characterized by indices taking values in group cohomology of G or the cohomology of X\, respectively. The situation where one has both a symmetry and a parametrization is much less studied but can lead to interesting phases even when both the aforementioned indices are trivial. In this talk\, I will discuss work in progress on a simple construction for general index for symmetry protected parametrized systems of matrix product states and will show some illustrative examples.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-42426/
LOCATION:CMSA Room G10\, 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-4.24.26-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260417T120000
DTEND;TZID=America/New_York:20260417T130000
DTSTAMP:20260430T225525
CREATED:20260212T190403Z
LAST-MODIFIED:20260409T160741Z
UID:10003906-1776427200-1776430800@cmsa.fas.harvard.edu
SUMMARY:Higgs and Coulomb branches: Geometry and Representation Theory
DESCRIPTION:Member Seminar \nSpeaker: Vasily Krylov \nTitle: Higgs and Coulomb branches: Geometry and Representation Theory \nAbstract: Higgs and Coulomb branches of quiver gauge theories form two important families of Poisson varieties that are expected to be exchanged under so-called 3D mirror symmetry. Quantized Coulomb branches are associative algebras deforming the algebras of functions on Coulomb branches. They are closely related to many important representation-theoretic structures\, such as Yangians\, quantum groups\, and Hecke algebras. In this talk\, I will discuss how 3D mirror symmetry\, together with other insights motivated by physics\, yields very explicit answers to purely representation-theoretic questions about representations of some of these quantum groups. Talk is based on joint works with Dinkins\, Karpov\, Klyuev\, and Lance.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-41726/
LOCATION:CMSA Room G10\, 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-4.17.26.docx.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260410T120000
DTEND;TZID=America/New_York:20260410T130000
DTSTAMP:20260430T225525
CREATED:20260212T190254Z
LAST-MODIFIED:20260330T200409Z
UID:10003905-1775822400-1775826000@cmsa.fas.harvard.edu
SUMMARY:Quantum topology from dynamics
DESCRIPTION:Member Seminar \nSpeaker: Sunghyuk Park\, CMSA \nTitle: Quantum topology from dynamics \nAbstract: Dynamics studies the long-term behavior of systems that evolve over time\, such as the famous Lorenz system.\nQuantum topology\, by contrast\, studies knots and low-dimensional manifolds through invariants that are usually constructed using representation-theoretic tools. In this talk\, I will explain how quantum invariants of knots and 3-manifolds can be recovered from the dynamics of certain three-dimensional flows. Time permitting\, I will also explain how this new bridge arises from ideas in topological string theory. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-41026/
LOCATION:CMSA Room G10\, 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-4.10.26-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260403T120000
DTEND;TZID=America/New_York:20260403T130000
DTSTAMP:20260430T225525
CREATED:20260212T190229Z
LAST-MODIFIED:20260331T190743Z
UID:10003904-1775217600-1775221200@cmsa.fas.harvard.edu
SUMMARY:Failures of Holographic Emergence
DESCRIPTION:Member Seminar \nSpeaker: Elliott Gesteau\, CMSA \nTitle: Failures of Holographic Emergence \nAbstract: Recent developments have taught us that some semiclassical spacetimes\, in particular those containing closed universe components\, cannot emerge from a holographic correspondence. In this talk\, I will explain how one can get to this conclusion by using either quantum information theory or properties of the large N limit of AdS/CFT\, and propose a criterion for detecting failures of spacetime emergence. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-4326/
LOCATION:CMSA Room G10\, 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-4.3.26.docx.1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260227T120000
DTEND;TZID=America/New_York:20260227T130000
DTSTAMP:20260430T225525
CREATED:20251223T204714Z
LAST-MODIFIED:20260223T194128Z
UID:10003867-1772193600-1772197200@cmsa.fas.harvard.edu
SUMMARY:Gauge theory\, from low dimensions to higher dimensions and back
DESCRIPTION:Member Seminar \nSpeaker: Saman Habibi Esfahani\, CMSA \nTitle: Gauge theory\, from low dimensions to higher dimensions and back \nAbstract: Almost thirty years ago\, Donaldson and Thomas proposed extending powerful ideas from gauge theory\, which had transformed the study of three- and four-dimensional manifolds\, to higher dimensions\, with the goal of defining new invariants of special holonomy manifolds. In this talk\, I will outline the main ideas behind this program\, mention some recent progress\, and describe the key obstacles that remain\, most notably non-compactness phenomena that make the analysis difficult.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-22726/
LOCATION:CMSA Room G10\, 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-2.27.26-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260220T120000
DTEND;TZID=America/New_York:20260220T130000
DTSTAMP:20260430T225525
CREATED:20251223T204654Z
LAST-MODIFIED:20260217T154410Z
UID:10003866-1771588800-1771592400@cmsa.fas.harvard.edu
SUMMARY:Theory of Task-Adapted Dynamics in Large Recurrent Neural Networks
DESCRIPTION:Member Seminar \nSpeaker: Blake Bordelon\, CMSA \nTitle: Theory of Task-Adapted Dynamics in Large Recurrent Neural Networks \nAbstract: Recurrent neural networks (RNNs) encode expressive and flexible dynamical systems which can adapt to perform tasks by modifying the internal connections between neurons. In this work we analyze the structure of the dynamical systems encoded in RNNs after being trained to perform a learning task. We derive a mean field theory of the dynamics of RNNs before and after learning. Our theory predicts heterogeneous activity and tuning of single neurons\, but precise\, deterministic predictions for population level autocorrelation and outputs of the network. Further\, our theory enables us to interpolate between different operating regimes for RNN learning including (1) reservoir computing regime where internal adaptations do not adapt to data as the model outputs fit the provided data and (2) a feature-learning where the internal dynamics of the network change significantly due to task learning and reflect temporal properties of the learning task. These different regimes exhibit different levels of chaotic activity\, oscillatory behaviors\, and length generalization properties as feature learning enables maintenance of temporal patterns over longer periods than the supervision period. We apply this theory to a biologically grounded motor learning task where a recurrent population is trained to output EMG signals from macaque motor units during an oriented reaching task. We find that many levels of feature-learning strength give rise to high quality fits of the EMG data\, resulting in a family of solutions that are compatible with the neural data. Based on work with David Clark\, Jacob Zavatone Veth\, and Cengiz Pehlevan.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-22026/
LOCATION:CMSA Room G10\, 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-2.20.26.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260213T120000
DTEND;TZID=America/New_York:20260213T130000
DTSTAMP:20260430T225525
CREATED:20251223T204554Z
LAST-MODIFIED:20260210T152049Z
UID:10003865-1770984000-1770987600@cmsa.fas.harvard.edu
SUMMARY:A leisurely stroll through the theory of adjunctions
DESCRIPTION:Member Seminar \nSpeaker: Lorenzo Riva\, Harvard CMSA \nTitle: A leisurely stroll through the theory of adjunctions \nAbstract: Adjoint functors (and\, more generally\, adjunctions in a 2-category) are ubiquitous in algebra and topology. In this talk I will give an overview of the basics of adjunctions\, with the ultimate goal being understanding the statement of the cobordism hypothesis. Time permitting\, I will talk about some recent work on a combinatorial construction yielding free adjunctions. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-21326/
LOCATION:CMSA Room G10\, 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-2.13.26.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260206T120000
DTEND;TZID=America/New_York:20260206T130000
DTSTAMP:20260430T225525
CREATED:20250203T163329Z
LAST-MODIFIED:20260204T153228Z
UID:10003712-1770379200-1770382800@cmsa.fas.harvard.edu
SUMMARY:Lie algebra cohomology and Seiberg-Witten theory
DESCRIPTION:Member Seminar \nSpeaker: Ahsan Khan\, Harvard CMSA \nTitle: Lie algebra cohomology and Seiberg-Witten theory \nAbstract: I will discuss how a certain (relative) Lie algebra cochain complex categorifies the Schur index of N=2 supersymmetric gauge theory. For the special case of Seiberg-Witten theory I will provide a conjectured description of this cohomology.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-2626/
LOCATION:CMSA Room G10\, 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-2.6.26.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250516T120000
DTEND;TZID=America/New_York:20250516T130000
DTSTAMP:20260430T225525
CREATED:20250218T161047Z
LAST-MODIFIED:20250513T152517Z
UID:10003714-1747396800-1747400400@cmsa.fas.harvard.edu
SUMMARY:Echo Chamber: RL Post-training Amplifies Behaviors Learned in Pretraining
DESCRIPTION:Member Seminar \nSpeaker: Samy Jelassi\, CMSA \nTitle: Echo Chamber: RL Post-training Amplifies Behaviors Learned in Pretraining \nAbstract: Reinforcement Learning has become a crucial step in training state-of-the-art language models such as DeepSeek-R1 for solving mathematical problems. In this talk\, I will first review the mechanisms of Reinforcement Learning fine-tuning. Then\, I will present a systematic end-to-end study of RL fine-tuning for mathematical reasoning\, training models entirely from scratch on different mixtures of fully open datasets and fine-tuning them with RL. Doing so allows us to investigate the effects of the pretraining data mixture on the behavior of RL\, and its interaction with the model size and choices of the algorithm hyperparameters. Our study reveals that RL algorithms consistently converge towards a dominant output distribution\, amplifying patterns in the pretraining data. We also find that models of different scales trained on the same data mixture will converge to distinct output distributions\, suggesting that there are scale-dependent biases in model generalization. \nThe second part of the talk is based on a joint work with Rosie Zhao\, Alex Meterez\, Cengiz Pehlevan\, Sham Kakade and Eran Malach: https://arxiv.org/abs/2504.07912 \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-51625/
LOCATION:CMSA Room G10\, 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-5.16.25.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250509T120000
DTEND;TZID=America/New_York:20250509T130000
DTSTAMP:20260430T225525
CREATED:20241211T195446Z
LAST-MODIFIED:20250506T153832Z
UID:10003649-1746792000-1746795600@cmsa.fas.harvard.edu
SUMMARY:Asset pricing with heterogeneous agents
DESCRIPTION:Member Seminar \nSpeaker: Sergiy Verstyuk\, Harvard CMSA \nTitle: Asset pricing with heterogeneous agents \nAbstract: This talk will introduce the basics of continuous-time finance\, discuss important existing theories and models\, as well as present some new asset pricing results in a setting with many heterogeneous investors. (Joint work with Puskar Mondal.) \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-5925/
LOCATION:CMSA Room G10\, 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-5.9.25.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250502T120000
DTEND;TZID=America/New_York:20250502T130000
DTSTAMP:20260430T225525
CREATED:20241211T195435Z
LAST-MODIFIED:20250428T151202Z
UID:10003650-1746187200-1746190800@cmsa.fas.harvard.edu
SUMMARY:Incentives for data sharing in federated learning
DESCRIPTION:Member Seminar \nSpeaker: Han Shao\, Harvard CMSA \nTitle: Incentives for data sharing in federated learning \nAbstract: Federated learning has recently emerged as a powerful approach for enabling collaboration across large populations of learning agents. However\, agents may have incentives to defect from the collaboration—that is\, to withdraw or contribute less data than expected—due to the costs of data curation and privacy concerns. This raises several key questions: What happens when agents defect\, and how can we prevent such defections? \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-5225/
LOCATION:CMSA Room G10\, 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-5.2.25.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250418T120000
DTEND;TZID=America/New_York:20250418T130000
DTSTAMP:20260430T225525
CREATED:20241211T195316Z
LAST-MODIFIED:20250218T160819Z
UID:10003647-1744977600-1744981200@cmsa.fas.harvard.edu
SUMMARY:Member Seminar
DESCRIPTION:Member Seminar \nSpeaker: Han Shao \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-41825/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250411T120000
DTEND;TZID=America/New_York:20250411T130000
DTSTAMP:20260430T225525
CREATED:20241211T195247Z
LAST-MODIFIED:20250407T150951Z
UID:10003646-1744372800-1744376400@cmsa.fas.harvard.edu
SUMMARY:Homological Invariants in Translation-Invariant Pauli Stabilizer Codes
DESCRIPTION:Member Seminar \nSpeaker: Bowen Yang \nTitle: Homological Invariants in Translation-Invariant Pauli Stabilizer Codes \nAbstract: Pauli stabilizer codes serve as foundational models in quantum error correction and the study of exotic quantum phases. In this talk\, we explore the application of homological methods to translationally invariant Pauli stabilizer codes with qudits of varying dimensions. We introduce a series of invariants\, termed charge modules\, and delve into their properties and physical interpretations. A key focus is on codes whose charge modules exhibit zero Krull dimension\, a condition indicative of the mobility of excitations. Notably\, we demonstrate that this condition is universally met in two-dimensional codes with a unique ground state in infinite volume\, extending prior findings beyond the realm of uniform\, prime qudit dimensions. For systems where all excitations are mobile\, we establish the existence of p-dimensional excitations and associated (D−p−1)-form symmetries corresponding to each element of the p-th charge module. Additionally\, we define a braiding pairing between charge modules in complementary degrees.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-41125/
LOCATION:CMSA Room G10\, 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-4.11.25.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250404T120000
DTEND;TZID=America/New_York:20250404T130000
DTSTAMP:20260430T225525
CREATED:20241211T195214Z
LAST-MODIFIED:20250328T164025Z
UID:10003645-1743768000-1743771600@cmsa.fas.harvard.edu
SUMMARY:Learning diffusion models in high-dimensions
DESCRIPTION:Member Seminar \nSpeaker: Hugo Cui \nTitle: Learning diffusion models in high-dimensions \nAbstract: We consider the problem of learning a generative model parametrized by a two-layer auto-encoder\, and trained with online stochastic gradient descent\, to sample from a high-dimensional data distribution with an underlying low-dimensional structure. We provide a tight asymptotic characterization of low-dimensional projections of the resulting generated density\, and evidence how mode(l) collapse can arise.  On the other hand\, we discuss how in a case where the architectural bias is suited to the target density\, these simple models can efficiently learn to sample from a binary Gaussian mixture target distribution. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-4425/
LOCATION:CMSA Room G10\, 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-4.4.25.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250328T120000
DTEND;TZID=America/New_York:20250328T130000
DTSTAMP:20260430T225525
CREATED:20241211T195142Z
LAST-MODIFIED:20250324T153000Z
UID:10003644-1743163200-1743166800@cmsa.fas.harvard.edu
SUMMARY:The Competition Complexity of Dynamic Pricing
DESCRIPTION:Member Seminar \nSpeaker: Tomer Ezra \nTitle: The Competition Complexity of Dynamic Pricing \nAbstract: One of the most fundamental questions in mechanism design is the tradeoff between simplicity and optimality. A canonical example of this tradeoff is competition complexity in auctions\, which quantifies how many additional bidders are needed for a simple mechanism to (approximately) match the revenue of the optimal mechanism. \nIn this talk\, we analyze the competition complexity of dynamic pricing in the setting of selling a single item. We establish tight asymptotic guarantees for various scenarios\, including when bidder values are i.i.d.\, independent\, or correlated. Our results characterize the performance of different classes of dynamic pricing algorithms and provide insights into their effectiveness under varying market conditions.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-32825/
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-3.28.25.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250307T120000
DTEND;TZID=America/New_York:20250307T130000
DTSTAMP:20260430T225525
CREATED:20241211T192236Z
LAST-MODIFIED:20250303T133212Z
UID:10003642-1741348800-1741352400@cmsa.fas.harvard.edu
SUMMARY:A Tetrahedral Approach to Calabi-Yau Geometry
DESCRIPTION:Member Seminar \nSpeaker: Charles Doran\, CMSA \nTitle: A Tetrahedral Approach to Calabi-Yau Geometry \nAbstract:  We will open with a quick introduction to the what and why of Calabi-Yau geometry.  Following this\, we will consider the problem of deforming tetrahedra while preserving the areas of their faces\, following our noses to discover a beautiful path to elliptic curves\, K3 surfaces\, and beyond.  Time permitting\, we will also discuss motivations and applications across physics.  The talk should be broadly accessible. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-3724/
LOCATION:CMSA Room G10\, 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-3.7.25.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250228T120000
DTEND;TZID=America/New_York:20250228T130000
DTSTAMP:20260430T225525
CREATED:20241211T172401Z
LAST-MODIFIED:20250225T155302Z
UID:10003641-1740744000-1740747600@cmsa.fas.harvard.edu
SUMMARY:The Combinatorics of the Amplituhedron – Tiles\, Tilings\, and Cluster Algebras
DESCRIPTION:Member Seminar \nSpeaker: Matteo Parisi \nTitle: The Combinatorics of the Amplituhedron – Tiles\, Tilings\, and Cluster Algebras \nAbstract: The amplituhedron is the image of the positive Grassmannian—the region of the Grassmannian where all Plücker coordinates are nonnegative—under a totally positive linear map. It is a far-reaching generalization of cyclic polytopes and hyperplane arrangements\, and the positive Grassmannian itself. The “volume” of the amplituhedron encodes probabilities of particle interactions in the quantum field theory N=4 super Yang-Mills\, and calculating this volume involves decomposing (or tiling) the amplituhedron into smaller pieces (or tiles) and summing their volumes. This talk will delve into the rich combinatorics of these tiles and tilings\, presenting recent results on some of the central conjectures in this area\, including the magic number\, BCFW tiling\, and cluster adjacency conjectures.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-22825/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/1740498728693-b34629b4-eb9a-47b2-9782-46abe1568dd025_1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250214T120000
DTEND;TZID=America/New_York:20250214T130000
DTSTAMP:20260430T225525
CREATED:20241211T171913Z
LAST-MODIFIED:20250210T162218Z
UID:10003640-1739534400-1739538000@cmsa.fas.harvard.edu
SUMMARY:Jack polynomials and enumeration of non-orientable maps
DESCRIPTION:Member Seminar \nSpeaker: Houcine Ben Dali\, Harvard CMSA \nTitle: Jack polynomials and enumeration of non-orientable maps \nAbstract: A map is a graph embedded on a surface\, which may be orientable or not. The representation theory of the symmetric group can be used to write the generating series of maps on orientable surfaces using Schur symmetric functions. \nSeveral conjectures suggest that Jack polynomials—a one-parameter deformation of Schur functions—are related to the enumeration of non-orientable maps counted with a “non-orientability” weight. In this talk\, I will discuss some of these conjectures and present recent progress in this direction.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-21425/
LOCATION:CMSA Room G10\, 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-2.14.25-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250131T120000
DTEND;TZID=America/New_York:20250131T130000
DTSTAMP:20260430T225526
CREATED:20250127T180141Z
LAST-MODIFIED:20250127T180704Z
UID:10003638-1738324800-1738328400@cmsa.fas.harvard.edu
SUMMARY:Smooth projective fibrations over the projective line and their sections
DESCRIPTION:Member Seminar \nSpeaker: Iacopo Brivio \nTitle: Smooth projective fibrations over the projective line and their sections \nAbstract: Suppose $f\colon X\to \mathbf{CP}^1$ is a smooth projective fibration\, is it then true that $f$ has a section? This deceptively simple result was established by Seidel and McDuff using deep methods of symplectic geometry. Alex Pieloch recently generalized this to morphisms with at most one singular fibers and furthermore showed that $X$ uniruled\, that is covered by images of $\mathbf{P}^1$. In my talk I will explain how to recover Pieloch’s result from the Good Minimal Model Conjecture. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-13125/
LOCATION:CMSA Room G10\, 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-1.31.25.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20241206T120000
DTEND;TZID=America/New_York:20241206T130000
DTSTAMP:20260430T225526
CREATED:20240919T144747Z
LAST-MODIFIED:20241203T164917Z
UID:10003527-1733486400-1733490000@cmsa.fas.harvard.edu
SUMMARY:On the Coulomb branch scaling dimensions of 4d N=2 SCFTs
DESCRIPTION:Member Seminar \nSpeaker: Robert Moscrop \nTitle: On the Coulomb branch scaling dimensions of 4d N=2 SCFTs \nAbstract: To each four dimensional N=2 superconformal field theory of rank-r\, one can associate an r-tuple of numbers given by the scaling dimensions of a special set of protected operators whose VEVs parameterise the Coulomb branch. In this talk\, I will demonstrate how the special geometry of the Coulomb branch heavily constrains not only the values of the scaling dimensions\, but also the possible r-tuples of such numbers that can occur.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-120624/
LOCATION:CMSA Room G10\, 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-12.6.24.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20241122T120000
DTEND;TZID=America/New_York:20241122T130000
DTSTAMP:20260430T225526
CREATED:20240919T144708Z
LAST-MODIFIED:20241118T172611Z
UID:10003525-1732276800-1732280400@cmsa.fas.harvard.edu
SUMMARY:Identity crises phenomena in the large cardinal hierarchy
DESCRIPTION:Member Seminar \nSpeaker: Alejandro Poveda \nTitle: Identity crises phenomena in the large cardinal hierarchy\n\nAbstract: It is well-known that certain mathematical questions cannot be answered on the grounds of the standard foundation of mathematics. Large cardinal axioms constitute a series of postulates about the higher infinite which permit to classify these undecidable problems in a coherent hierarchy way. Specifically\, large cardinals together with ZFC (the standard axiomatic of Mathematics) provide a complete classification of all mathematical theories according to the so-called consistency strength. One of the main tenets of modern set theory has been to investigate how the large-cardinal hierarchy is organized across the mathematical universe. To a large extent this hierarchy is nicely disposed and such a disposition is unambiguous (i.e.\, immune to the independence phenomenon).\n\nIn an unexpected turn of events\, in the late 70’s Magidor discovered the identity crisis phenomena of the large cardinal hierarchy. Magidor proved that certain strata of the hierarchy are susceptible to be modified via Cohen’s method of forcing. Specifically\, he showed that the first strongly compact cardinal can be either the first measurable cardinal or the first supercompact cardinal. It turns out that the first measurable is always much smaller than the first supercompact. These discrepancies on the identity of the first strongly compact cardinal were termed by Magidor the Identity Crisis Phenomenon.\n\nIn this talk I plan to provide an introduction to the world of large cardinals keeping an eye on the identity crises phenomena. Time permitting\, I’ll present a few recent results answering questions by Magidor and discuss their connection with Woodin’s Ultimate-L Conjecture.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-112224/
LOCATION:CMSA Room G10\, 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-11.22.24_Page_1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20241115T120000
DTEND;TZID=America/New_York:20241115T130000
DTSTAMP:20260430T225526
CREATED:20240919T144643Z
LAST-MODIFIED:20241115T144349Z
UID:10003524-1731672000-1731675600@cmsa.fas.harvard.edu
SUMMARY:Quantum Criticality in Black Hole Scattering
DESCRIPTION:Member Seminar \nSpeaker: Uri Kol \nTitle: Quantum Criticality in Black Hole Scattering \nAbstract: Perturbation theory around rotating black holes captures a few important effects in the physics of gravitational waves emitted from binary mergers. Despite a long and rich history\, developing a qualitative understanding of the system remains a challenging problem. In this talk I will describe an emergent critical phenomena arising in black hole perturbation theory\, which is reminiscent of the structure found in quantum many-body systems. A critical point is identified at zero temperature\, giving rise to a wide “quantum” critical region at finite temperatures that is dominated by critical fluctuations. In the critical region\, the physics is exclusively described by a set of critical exponents\, therefore leading to robust predictions. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-111524/
LOCATION:CMSA Room G10\, 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-11.15.24.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20241108T120000
DTEND;TZID=America/New_York:20241108T130000
DTSTAMP:20260430T225526
CREATED:20240919T144552Z
LAST-MODIFIED:20241105T154430Z
UID:10003523-1731067200-1731070800@cmsa.fas.harvard.edu
SUMMARY:ADHM spaces and their quantizations
DESCRIPTION:Member Seminar \nSpeaker: Vasily Krylov\, CMSA \nTitle: ADHM spaces and their quantizations \nAbstract: In their paper “Construction of Instantons\,” Atiyah\, Drinfeld\, Hitchin\, and Manin introduced an algebraic construction of the moduli space of instantons on R^4\, now also known as the “ADHM space.” This is a Poisson complex variety; it has been actively studied by both mathematicians and physicists. In this talk\, I will review the ADHM construction\, present examples\, and discuss various geometric and algebraic properties of ADHM spaces. I will also describe natural quantizations of these Poisson varieties. I will explain a joint result with Etingof\, Losev\, and Simental\, providing explicit formulas for the dimensions and characters of all finite-dimensional representations of these quantizations. Time permitting\, I will illustrate some predictions of the 3D mirror symmetry in the example of ADHM spaces\, following our joint paper with Shlykov.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-11824/
LOCATION:CMSA Room G10\, 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-11.8.24.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20241025T120000
DTEND;TZID=America/New_York:20241025T130000
DTSTAMP:20260430T225526
CREATED:20240919T144515Z
LAST-MODIFIED:20241022T155009Z
UID:10003522-1729857600-1729861200@cmsa.fas.harvard.edu
SUMMARY:Formality Theorem and Webs
DESCRIPTION:Member Seminar \nSpeaker: Ahsan Khan \nTitle: Formality Theorem and Webs \nAbstract: The “formality theorem” of Kontsevich was a key result that implies that every Poisson manifold admits a deformation quantization. I will review the ideas behind the formality theorem and discuss a potentially novel viewpoint on it involving webs and twisted masses.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-102524/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Member Seminar
ATTACH;FMTTYPE=application/pdf:https://cmsa.fas.harvard.edu/media/CMSA-Member-Seminar-10.25.24.docx.pdf
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20241018T120000
DTEND;TZID=America/New_York:20241018T130000
DTSTAMP:20260430T225526
CREATED:20240919T144412Z
LAST-MODIFIED:20241015T180358Z
UID:10003521-1729252800-1729256400@cmsa.fas.harvard.edu
SUMMARY:Positive mass and rigidity theorems in Riemannian geometry  
DESCRIPTION:Member Seminar \nSpeaker: Puskar Mondal \nTitle: Positive mass and rigidity theorems in Riemannian geometry \nAbstract: Positive mass theorem proved by Schoen-Yau\, Witten\, Taubes-Parker is one of the most important results in scalar curvature geometry in asymptotically flat settings. Since then several versions have been proven and generalized to other geometries such as asymptotically hyperbolic manifolds. The analogous theorem for strictly positive curvature geometries is absent. There have been counterexamples but a precise quantification does not exist.I prove a scalar curvature rigidity theorem for spheres. In particular\, I prove that $n+1~(n\geq 2)$ dimensional spherical caps with constant positive mean curvature totally umbilic boundaries are rigid under smooth perturbations\, and such rigidity results fail for the hemisphere. The assertion of this result is based on the notion of a real Killing connection and solution of the boundary value problem associated with its Dirac operator. Additionally\, an improved eigenvalue estimate for the Dirac operator on hypersurfaces in positively curved manifolds is obtained.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-101824/
LOCATION:CMSA Room G10\, 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-10.18.24.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20241011T120000
DTEND;TZID=America/New_York:20241011T130000
DTSTAMP:20260430T225526
CREATED:20240919T144307Z
LAST-MODIFIED:20241008T132658Z
UID:10003520-1728648000-1728651600@cmsa.fas.harvard.edu
SUMMARY:Scattering Amplitude from a Twistor Point of View
DESCRIPTION:Member Seminar \nSpeaker: Keyou Zeng \nTitle: Scattering Amplitude from a Twistor Point of View \nAbstract: Scattering amplitude is a key quantity in quantum field theory. Although challenging to compute at higher loops and for large particle numbers\, physicists have developed various tools to gain a deeper understanding of amplitudes. In this seminar\, I will introduce a novel approach\, initiated by K. Costello and N. Paquette\, which makes use of twistor correspondence. This approach enables the computation of certain amplitudes using chiral algebra. I will also present an upcoming work that constructs a top-down holography model for computing tree and loop amplitudes of certain non-SUSY theories in various self-dual backgrounds.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-101124/
LOCATION:CMSA Room G10\, 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-10.11.24.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20241004T120000
DTEND;TZID=America/New_York:20241004T130000
DTSTAMP:20260430T225526
CREATED:20240907T183353Z
LAST-MODIFIED:20240930T155114Z
UID:10003464-1728043200-1728046800@cmsa.fas.harvard.edu
SUMMARY:High-dimensional learning of narrow neural networks
DESCRIPTION:Member Seminar \nSpeaker: Hugo Cui\, CMSA \nTitle: High-dimensional learning of narrow neural networks \nAbstract: This talk explores the interplay between neural network architectures and data structure through the lens of high-dimensional asymptotics. We focus on a class of narrow neural networks\, namely networks possessing a finite number of hidden units\, while operating in high dimensions. In the limit of large data dimension and comparably large number of samples\, we derive a tight asymptotic characterization of the learning of these architectures. As an illustration\, we discuss how this characterization enables the analysis of a solvable model of dot-product attention. We show how the latter can learn to implement either a positional attention mechanism (with tokens attending to each other based on their respective positions)\, or a semantic attention mechanism (with tokens attending to each other based on their meaning)\, and evidence a phase transition with sample complexity from positional to semantic learning.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-10424/
LOCATION:CMSA Room G10\, 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-10.4.24.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240920T120000
DTEND;TZID=America/New_York:20240920T130000
DTSTAMP:20260430T225526
CREATED:20240907T183145Z
LAST-MODIFIED:20240916T164559Z
UID:10003462-1726833600-1726837200@cmsa.fas.harvard.edu
SUMMARY:Communication Complexity of Combinatorial Auctions
DESCRIPTION:Member Seminar \nSpeaker: Tomer Ezra (CMSA) \nTitle: Communication Complexity of Combinatorial Auctions \nAbstract: We study the communication complexity of welfare maximization in combinatorial auctions with m items and two subadditive bidders. A 2-approximation can be guaranteed by a trivial randomized protocol with zero communication\, or a trivial deterministic protocol with O(1) communication. We show that outperforming these trivial protocols requires exponential communication\, settling an open question of [DobzinskiNS10\, Feige09]. \nSpecifically\, we show that any (randomized) protocol guaranteeing a o(logm)-approximation requires communication exponential in m. We complement it by presenting an O(logm)-approximation in poly(m) communication.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-92024/
LOCATION:CMSA Room G10\, 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-09.20.24.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240913T120000
DTEND;TZID=America/New_York:20240913T130000
DTSTAMP:20260430T225526
CREATED:20240907T183113Z
LAST-MODIFIED:20240911T193907Z
UID:10003414-1726228800-1726232400@cmsa.fas.harvard.edu
SUMMARY:Abundance for mixed characteristic threefolds
DESCRIPTION:Member Seminar \nSpeaker: Iacopo Brivio (CMSA) \nTitle: Abundance for mixed characteristic threefolds \nAbstract: The Minimal Model Program (MMP) predicts that every algebraic variety X is birational to either a fibration in Fano varieties\, or it admits a “minimal model” X’\, that is a birational model with nef canonical bundle K_X’. The Abundance conjecture predicts then that K_X’ is actually semiample\, in particular it endows X’ with the structure of a Calabi-Yau fibration. These conjectures were initially phrased for complex varieties\, but more recently there has been a lot of interest in working over positive characteristic fields\, or even mixed characteristic rings. In this talk I will give a broad overview of the subject\, starting from the case of complex surfaces. In the last part I will outline a proof of the Abundance conjecture for mixed characteristic threefolds (based on joint work with F. Bernasconi and L. Stigant).
URL:https://cmsa.fas.harvard.edu/event/member-seminar_91324/
LOCATION:CMSA Room G10\, 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-09.13.24.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240514T123000
DTEND;TZID=America/New_York:20240514T133000
DTSTAMP:20260430T225526
CREATED:20240424T200426Z
LAST-MODIFIED:20240510T202406Z
UID:10003382-1715689800-1715693400@cmsa.fas.harvard.edu
SUMMARY:Quasilocal mass for general domains in space
DESCRIPTION:CMSA Member Seminar \nSpeaker: Jue Liu \nTitle: Quasilocal mass for general domains in space \nAbstract: Diffeomorphism-invariant quasilocal mass in classical general relativity has been studied for decades\, but it is still an open problem how to define quasi-local mass for general domains with multiple boundaries in space. Using the Hamiltonian formulation\, we will provide a new way to define the nonnegative quasi-local mass\, and give recent progress in overcoming the difficulties.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-51424/
LOCATION:CMSA Room G10\, 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-05.14.24.png
END:VEVENT
END:VCALENDAR