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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260501T120000
DTEND;TZID=America/New_York:20260501T130000
DTSTAMP:20260501T223232
CREATED:20260212T190507Z
LAST-MODIFIED:20260430T140830Z
UID:10003908-1777636800-1777640400@cmsa.fas.harvard.edu
SUMMARY:Lifting F-split surfaces to the Witt vectors
DESCRIPTION:Member Seminar \nSpeaker: Iacopo Brivio\, CMSA \nTitle: Lifting F-split surfaces to the Witt vectors\n\nAbstract: Algebraic varieties in positive characteristic are ill behaved compared to characteristic zero ones. Several important tools available over the complex numbers\, such as the Hodge decomposition theorem\, are either not available or straight-away false. There are two important classes of positive characteristic varieties which have better behavior: Witt liftable varieties and Frobenius split varieties. A folklore conjecture predicts that the latter class is contained in the former. In a joint work with Bernasconi\, Kawakami and Witaszek we proved that this is the case for surfaces. I will give an overview of this result as well as some applications thereof.\n  \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-5126/
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-5.1.26.docx.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260504T150000
DTEND;TZID=America/New_York:20260504T160000
DTSTAMP:20260501T223232
CREATED:20260126T190454Z
LAST-MODIFIED:20260430T170629Z
UID:10003880-1777906800-1777910400@cmsa.fas.harvard.edu
SUMMARY:Twisted D-branes and TQFTs valued in Calabi-Yau categories
DESCRIPTION:Quantum Field Theory and Physical Mathematics Seminar \nSpeaker: Surya Raghavendran\, Yale University \nTitle: Twisted D-branes and TQFTs valued in Calabi-Yau categories \nAbstract: Recently\, Bozec–Calaque–Scherotzke have articulated a noncommutative version of the AKSZ construction\, which associates to a smooth Calabi–Yau category a fully extended TQFT valued in a category of iterated Calabi–Yau cospans. In this talk\, I will study a class of examples of such theories which arise in the context of conjectures of Costello and Li\, which describe Type II strings in certain Ramond–Ramond backgrounds as topological strings. These TQFTs capture structural features of the BPS physics of D-branes that are universal in Chan–Paton factors. Conjecturally commutative limits of the values of such theories on closed manifolds can sometimes be geometrically quantized to yield algebraic structures with Hall-type products. Examples of this paradigm include CoHAs associated to complex 3-folds\, CoHAs attached to local systems on 3-manifolds\, and the categorified Hall algebras of Porta–Sala.
URL:https://cmsa.fas.harvard.edu/event/qft_5426/
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-5.4.26.docx.edit_-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260504T163000
DTEND;TZID=America/New_York:20260504T173000
DTSTAMP:20260501T223232
CREATED:20260323T160718Z
LAST-MODIFIED:20260421T135719Z
UID:10003923-1777912200-1777915800@cmsa.fas.harvard.edu
SUMMARY:Dynamics as intersection problem
DESCRIPTION:Colloquium \nSpeaker: Nikita Nekrasov\, Simons Center \nTitle: Dynamics as intersection problem \nAbstract: Most classical and quantum field theories are based on an action principle. However\, there are important exceptions to this — hydrodynamics and the theory of self-dual fields. In this talk we formulate the covariant relativistic fluid dynamics\, with or without magnetic fields\, as well as the theory of chiral boson in 1+1 dimensions\, self-dual tensor in 1+5 dimensions\, and self-dual four-form of IIB supergravity\, in terms of intersection theory of an auxiliary phase space. This provides a common covariant geometric framework for systems without a conventional action\, while at the same time laying the groundwork for quantization via the Kontsevich approach. Joint work with Paul Wiegmann. \n  \n 
URL:https://cmsa.fas.harvard.edu/event/colloquium-5426/
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-5.4.2026.docx.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260506T140000
DTEND;TZID=America/New_York:20260506T150000
DTSTAMP:20260501T223232
CREATED:20260421T144955Z
LAST-MODIFIED:20260421T150144Z
UID:10003935-1778076000-1778079600@cmsa.fas.harvard.edu
SUMMARY:New directions in synthetic data
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Tatsunori Hashimoto\, Stanford \nTitle: New directions in synthetic data \nAbstract: Synthetic data has been an effective\, if boring set of techniques: prompt some language model to restructure your corpus to match some downstream task\, with occasionally some distillation. In this talk\, we will take a more expansive view of synthetic data as a general algorithmic tool for generative modeling\, arguing that the design space and possibilities of synthetic data are much bigger than it might seem. Through a few recent works\, we will show that synthetic data has major benefits beyond transforming the data – improving in-domain perplexities\, and enabling unique algorithmic primitives\, such as neighborhood smoothing and concatenated ‘mega’ documents. With this broader view\, we will point towards a nascent but interesting possibility of treating data itself as an algorithmic object to be engineered and optimized end-to-end. \n 
URL:https://cmsa.fas.harvard.edu/event/newtech_5626/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-5.6.2026.docx.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260511T150000
DTEND;TZID=America/New_York:20260511T160000
DTSTAMP:20260501T223232
CREATED:20260409T140454Z
LAST-MODIFIED:20260409T140554Z
UID:10003931-1778511600-1778515200@cmsa.fas.harvard.edu
SUMMARY:Quantum Field Theory and Physical Mathematics
DESCRIPTION:Quantum Field Theory and Physical Mathematics Seminar \n 
URL:https://cmsa.fas.harvard.edu/event/qft_51126/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Field Theory and Physical Mathematics
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260511T163000
DTEND;TZID=America/New_York:20260511T173000
DTSTAMP:20260501T223232
CREATED:20251223T190403Z
LAST-MODIFIED:20260409T200727Z
UID:10003848-1778517000-1778520600@cmsa.fas.harvard.edu
SUMMARY:Statistical Shape Analysis of Complex Natural Structures
DESCRIPTION:Colloquium \nSpeaker: Anuj Srivastava\, Johns Hopkins University \nTitle: Statistical Shape Analysis of Complex Natural Structures \nAbstract: Statistical modeling and analysis of structured data is a fast-growing field in Statistics and Data Science. Rapid advances in imaging techniques have led to tremendous amounts of data for analyzing imaged objects across several scientific disciplines. Examples include shapes of cancer cells\, botanical trees\, human biometrics\, 3D genome\, brain anatomical structures\, crowd videos\, nano-manufacturing\, and so on. Shapes are relevant even in non-imaging data contexts\, e.g.\, the shapes of COVID rate curves or the shapes of activity cycles in lifestyle data. Imposing statistical models and inferences on shapes seems daunting because the shape is an abstract notion and one requires precise mathematical representations to quantify shapes. This talk has two parts. In the first part\, I will present some recent developments in “elastic representations” of structures such as functions\, curves\, surfaces\, and graphs. In the second part\, I will focus on statistical analyses: computing shape summaries\, estimation under shape constraints\, hypothesis testing\, time-series models\, and regression models involving shapes. \n 
URL:https://cmsa.fas.harvard.edu/event/colloquium-51126/
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-5.11.2026.docx.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260514T160000
DTEND;TZID=America/New_York:20260514T170000
DTSTAMP:20260501T223232
CREATED:20260330T154547Z
LAST-MODIFIED:20260501T204845Z
UID:10003926-1778774400-1778778000@cmsa.fas.harvard.edu
SUMMARY:Polynomial invariants of conjugation over finite fields
DESCRIPTION:Algebra Seminar \nSpeaker: Aryaman Maithani\, University of Utah \nTitle: Polynomial invariants of conjugation over finite fields\n\nAbstract: Consider the conjugation action of GL₂(K) on the polynomial ring K[X₂ₓ₂].\nWhen K is an infinite field\, the ring of invariants is a polynomial ring generated by the trace and the determinant.\nWe describe the ring of invariants when K is a finite field\, and show that it is a hypersurface.\n  \n 
URL:https://cmsa.fas.harvard.edu/event/algebra-seminar_51426/
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-5.14.26.docx-scaled.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260518T150000
DTEND;TZID=America/New_York:20260518T160000
DTSTAMP:20260501T223232
CREATED:20260413T151244Z
LAST-MODIFIED:20260413T151244Z
UID:10003933-1779116400-1779120000@cmsa.fas.harvard.edu
SUMMARY:Quantum Field Theory and Physical Mathematics
DESCRIPTION:Quantum Field Theory and Physical Mathematics Seminar \n 
URL:https://cmsa.fas.harvard.edu/event/qft_51826/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Field Theory and Physical Mathematics
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20260520T140000
DTEND;TZID=America/New_York:20260520T150000
DTSTAMP:20260501T223232
CREATED:20260429T133019Z
LAST-MODIFIED:20260429T143145Z
UID:10003942-1779285600-1779289200@cmsa.fas.harvard.edu
SUMMARY:Separation of timescales controls feature learning and overfitting in large neural networks
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Pierfrancesco Urbani\, Universite Paris-Saclay\, CNRS\, CEA\, Institut de physique theorique \nTitle: Separation of timescales controls feature learning and overfitting in large neural networks \nAbstract: To understand the inductive bias and generalization capabilities of large\, overparameterized machine learning models\, it is essential to analyze the dynamics of their training algorithms. Using dynamical mean field theory we investigate the learning dynamics of large two-layer neural networks. Our findings reveal that\, for networks with a large width\, the training process exhibits a separation of timescales phenomenon. This leads to several key observations:\n1. The emergence of a slow timescale linked to the growth in Gaussian/Rademacher complexity of the network;\n2. An inductive bias favoring low complexity when the initial model complexity is sufficiently small;\n3. A dynamical decoupling between feature learning and overfitting phases;\n4. A non-monotonic trend in test error\, characterized by a “feature unlearning” regime at later stages of training.\nJoint work with Andrea Montanari. \n  \n 
URL:https://cmsa.fas.harvard.edu/event/newtech_52026/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-NTM-Seminar-5.20.2026.docx.png
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