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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20250404T120000
DTEND;TZID=America/New_York:20250404T130000
DTSTAMP:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20260427T155642
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:20240516T103000
DTEND;TZID=America/New_York:20240516T113000
DTSTAMP:20260427T155642
CREATED:20240416T133753Z
LAST-MODIFIED:20240514T183407Z
UID:10003374-1715855400-1715859000@cmsa.fas.harvard.edu
SUMMARY:Mirror symmetry and log del Pezzo surfaces
DESCRIPTION:Algebraic Geometry in String Theory Seminar \nSpeaker: Franco Rota\, University of Glasgow \nTitle: Mirror symmetry and log del Pezzo surfaces \nAbstract: The homological mirror symmetry conjecture predicts a duality\, expressed in terms of categorical equivalences\, between the complex geometry of a variety X (the B side) and the symplectic geometry of its mirror object Y (the A side). Motivated by this\, we study a series of singular surfaces (called log del Pezzo). I will describe the category arising in the B side\, using the McKay correspondence and explicit birational geometry. I will discuss early results on the A side\, using the language of pseudolattices to focus on the special case of a smooth degree 2 del Pezzo surface. This is joint work with Giulia Gugiatti.
URL:https://cmsa.fas.harvard.edu/event/agist_51624/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Algebraic-Geometry-in-String-Theory-05.16.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240514T123000
DTEND;TZID=America/New_York:20240514T133000
DTSTAMP:20260427T155642
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
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240510T120000
DTEND;TZID=America/New_York:20240510T130000
DTSTAMP:20260427T155642
CREATED:20240416T185907Z
LAST-MODIFIED:20240507T190133Z
UID:10000695-1715342400-1715346000@cmsa.fas.harvard.edu
SUMMARY:On the landscape of 4d N=2 SCFTs
DESCRIPTION:CMSA Member Seminar \nSpeaker: Robert Moscrop\, Harvard CMSA \nTitle: On the landscape of 4d N=2 SCFTs \nAbstract: Four-dimensional conformal field theories with sufficient (N = 2) supersymmetry are highly constrained. So much so\, there has been an ongoing effort to classify them using only information about their moduli space of vacua. In this talk\, I will review recent progress in this classification before detailing a subclass of theories for which the classification problem is particularly tractable.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-51024/
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-05.10.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240509T103000
DTEND;TZID=America/New_York:20240509T113000
DTSTAMP:20260427T155642
CREATED:20240416T133629Z
LAST-MODIFIED:20240507T152049Z
UID:10000890-1715250600-1715254200@cmsa.fas.harvard.edu
SUMMARY:Computing periods of hypersurfaces and elliptic surfaces via effective homology
DESCRIPTION:Algebraic Geometry in String Theory Seminar \nSpeaker: Eric Pichon-Pharabod\, Universite Paris-Saclay \nTitle: Computing periods of hypersurfaces and elliptic surfaces via effective homology \nAbstract: The period matrix of a smooth complex projective variety X encodes the isomorphism between its singular homology and its algebraic De Rham cohomology. Numerical approximations with sufficient precision of the entries of this matrix\, called periods\, allow to recover some algebraic invariants of the variety\, such as the Néron-Severi group in the case of surfaces. In this talk\, we will present a method relying on the computation of an effective description of the homology for obtaining such numerical approximations of the periods of hypersurfaces and elliptic surfaces.
URL:https://cmsa.fas.harvard.edu/event/agst-5924/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Algebraic-Geometry-in-String-Theory-05.09.2024.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240507T120000
DTEND;TZID=America/New_York:20240507T130000
DTSTAMP:20260427T155642
CREATED:20240207T190343Z
LAST-MODIFIED:20240813T155522Z
UID:10000693-1715083200-1715086800@cmsa.fas.harvard.edu
SUMMARY:On using ML for Economics
DESCRIPTION:CMSA Member Seminar \nSpeaker: Sergiy Verstyuk \nTitle: On using ML for Economics \nAbstract: I will introduce some tools from the field of machine learning and discuss how they can be leveraged to get a fresh perspective on economics.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-5724/
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-05.07.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240426T120000
DTEND;TZID=America/New_York:20240426T130000
DTSTAMP:20260427T155642
CREATED:20240305T160053Z
LAST-MODIFIED:20240416T185829Z
UID:10000691-1714132800-1714136400@cmsa.fas.harvard.edu
SUMMARY:Member Seminar
DESCRIPTION:CMSA Member Seminar \nSpeaker: Matteo Parisi\, Harvard CMSA
URL:https://cmsa.fas.harvard.edu/event/member-seminar-42624/
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:20240425T103000
DTEND;TZID=America/New_York:20240425T113000
DTSTAMP:20260427T155642
CREATED:20240416T133525Z
LAST-MODIFIED:20240422T185259Z
UID:10000888-1714041000-1714044600@cmsa.fas.harvard.edu
SUMMARY:The logarithmic double ramification locus
DESCRIPTION:Algebraic Geometry in String Theory Seminar \nSpeaker: Alessandro Chiodo\, IMJ-Paris Rive Gauche (Jussieu) \nTitle: The logarithmic double ramification locus \nAbstract: Given a family of smooth curves C -> S with a line bundle L on C\, it is natural to study the locus of points x in S where L_x is trivial on C_x. When the family is stable\, the definition can be extended\, not directly on the base scheme S\, but more naturally on a (logarithmic) blow-up S’ of S. The problem is in many ways analogue to the problem of defining a Néron model on the moduli space of stable curves (instead of a DVR). Over the past years\, David Holmes and his collaborators pioneered a new approach on a logarithmic modification of the entire moduli space of curves. In this talk\, we determine this logarithmic double ramification cycle and several variants and alternative presentations of it (work in collaboration with David Holmes).
URL:https://cmsa.fas.harvard.edu/event/agst-42524/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Algebraic-Geometry-in-String-Theory-04.25.2024.docx-2.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240419T120000
DTEND;TZID=America/New_York:20240419T130000
DTSTAMP:20260427T155642
CREATED:20240305T155850Z
LAST-MODIFIED:20240418T194607Z
UID:10000689-1713528000-1713531600@cmsa.fas.harvard.edu
SUMMARY:Member Seminar
DESCRIPTION:CMSA Member Seminar \nSpeaker: Sunghyuk Park\, Harvard CMSA \nTitle: 3D quantum trace map \nAbstract: I will speak about my recent work (joint with Sam Panitch) constructing the 3d quantum trace map\, a homomorphism from the Kauffman bracket skein module of an ideally triangulated 3-manifold to its (square root) quantum gluing module\, thereby giving a precise relationship between the two quantizations of the character variety of ideally triangulated 3-manifolds. Our construction is based on the study of stated skein modules and their behavior under splitting\, especially into face suspensions. \n 
URL:https://cmsa.fas.harvard.edu/event/member-seminar-41924/
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-04.19.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240418T101500
DTEND;TZID=America/New_York:20240418T113000
DTSTAMP:20260427T155642
CREATED:20240415T133328Z
LAST-MODIFIED:20240813T153315Z
UID:10000887-1713435300-1713439800@cmsa.fas.harvard.edu
SUMMARY:Geometric local systems on very general curves
DESCRIPTION:Algebraic Geometry in String Theory Seminar \nSpeaker: Aaron Landesman\, MIT \nTitle: Geometric local systems on very general curves \nAbstract: What is the smallest genus h of a non-isotrivial curve over the generic genus g curve? In joint work with Daniel Litt\, we show h is more than $\sqrt{g}$ by proving amore general result about variations of Hodge structure on sufficiently general curves. As a consequence\, we show that local systems on a sufficiently general curve of geometric origin are not Zariski dense in the character variety parameterizing such local systems. This gives counterexamples to conjectures of Esnault-Kerz and Budur-Wang.
URL:https://cmsa.fas.harvard.edu/event/agst-41824/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Algebraic-Geometry-in-String-Theory-04.18.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240412T120000
DTEND;TZID=America/New_York:20240412T130000
DTSTAMP:20260427T155642
CREATED:20240305T155803Z
LAST-MODIFIED:20240410T234826Z
UID:10000687-1712923200-1712926800@cmsa.fas.harvard.edu
SUMMARY:Global weak solutions of 3+1 dimensional vacuum Einstein equations 
DESCRIPTION:CMSA Member Seminar \nSpeaker: Puskar Mondal \nTitle: Global weak solutions of 3+1 dimensional vacuum Einstein equations \nAbstract: It is important to understand if the `solutions’ of non-linear evolutionary PDEs persist for all time or become extinct in finite time through the blow-up of invariant entities. Now the question of this global existence or finite time blow up in the PDE settings is well defined if the regularity of the solution is specified. Most physically interesting scenarios demand control of the point-wise behavior of the solution. Unfortunately\, most times this level of regularity is notoriously difficult to obtain for non-linear equations. In this talk\, I will discuss very low regularity solutions namely distributional (or weak) solutions of vacuum Einsten’s equations in 3+1 dimensions. I prove that on a globally hyperbolic spacetime foliated by closed connected oriented negative Yamabe slices\, weak solutions of the Einstein equations exist for all time. The monotonicity of a Coercive Entity called reduced Hamiltonian that controls the minimum regularity required for the weak solution is employed. This is in the same spirit as Leray’s global weak solutions of Navier-Stokes in 3+1 dimensions and the first result in the context of Einstein equations.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-41224/
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-04.12.2024.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240411T103000
DTEND;TZID=America/New_York:20240411T113000
DTSTAMP:20260427T155642
CREATED:20240410T234504Z
LAST-MODIFIED:20240410T234742Z
UID:10000886-1712831400-1712835000@cmsa.fas.harvard.edu
SUMMARY:Mirror symmetry for fibrations and degenerations of K3 surfaces
DESCRIPTION:Algebraic Geometry in String Theory Seminar \nSpeaker: Alan Thompson (Loughborough University) \nTitle: Mirror symmetry for fibrations and degenerations of K3 surfaces \nAbstract: In 2016\, Doran\, Harder\, and I conjectured a mirror symmetric relationship between Tyurin degenerations and splittings of codimension 1 fibrations on Calabi-Yau manifolds. In this talk I will discuss recent work to make this conjecture rigorous in the case of K3 surfaces. I will give a precise definition of what it means for a Tyurin degeneration of K3’s to be mirror to a splitting of an elliptically fibred K3\, and show that this definition enjoys the following compatibilities with existing mirror symmetric theories: 1) The general fibre of the Tyurin degeneration is mirror to the elliptically fibred K3\, in the sense of Dolgachev-Nikulin. 2) Components of the Tyurin degeneration and pieces of the splitting satisfy a homological version of the (quasi-) Fano-LG correspondence. 3) Components of the Tyurin degeneration which are weak del Pezzo are mirror to pieces of the splitting that arise as restrictions of the corresponding lattice polarised LG models to discs. This is joint work with Luca Giovenzana.
URL:https://cmsa.fas.harvard.edu/event/agst-41124/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Algebraic-Geometry-in-String-Theory-04.11.2024_Page_1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240405T120000
DTEND;TZID=America/New_York:20240405T130000
DTSTAMP:20260427T155642
CREATED:20240213T165524Z
LAST-MODIFIED:20240403T143010Z
UID:10000685-1712318400-1712322000@cmsa.fas.harvard.edu
SUMMARY:Phase diagram and confining strings in a minimal model of nematopolar matter
DESCRIPTION:CMSA Member Seminar \nSpeaker: Farzan Vafa \nTitle: Phase diagram and confining strings in a minimal model of nematopolar matter \nAbstract: We investigate a minimal model of a nematopolar system. We analytically uncover a phase diagram consisting of a locked phase where the polar order and nematic order are locked\, and unlocked phases which could be ordered or disordered. In particular\, we develop two complementary perspectives on the locked phase: (i) the nematic order induces polar order\, (ii) in the locked phase\, all 1/2 integral nematic topological charges are confined. In particular\, a polar +1 defect fattens from a point along a string with constant tension and confines a pair of nematic +1/2 defects at its ends.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-4524/
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-04.05.2024.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240404T103000
DTEND;TZID=America/New_York:20240404T113000
DTSTAMP:20260427T155642
CREATED:20240325T190117Z
LAST-MODIFIED:20240326T153652Z
UID:10000885-1712226600-1712230200@cmsa.fas.harvard.edu
SUMMARY:Derived categories of genus one curves and torsors over abelian varieties
DESCRIPTION:Algebraic Geometry in String Theory Seminar \nSpeaker: Jonathan Rosenberg\, University of Maryland \n\nTitle: Derived categories of genus one curves and torsors over abelian varieties\n \nAbstract:  Studying orientifold string theories on elliptic curves or abelian\nvarieties motivates studying the derived category of coherent sheaves on\na genus one curve or a torsor over an abelian variety over the reals\n(as opposed to the complex numbers).\n\nIn joint work with Nirnajan Ramachandran (to appear in MRL)\, we show that\na genus one curve over a perfect field determines a class in the relative\nBrauer group of the Jacobian elliptic curve\, and that there is a natural\nMukai-type derived equivalence between the original genus one curve\nand the Jacobian twisted by the Brauer class.  The proof extends to\ntorsors over abelian varieties (of any dimension).
URL:https://cmsa.fas.harvard.edu/event/agst-4224/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Algebraic-Geometry-in-String-Theory-04.04.24-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20240322T120000
DTEND;TZID=America/New_York:20240322T130000
DTSTAMP:20260427T155642
CREATED:20240213T165334Z
LAST-MODIFIED:20240321T200536Z
UID:10000681-1711108800-1711112400@cmsa.fas.harvard.edu
SUMMARY:Modularity and Fibrations in Mirror Symmetry
DESCRIPTION:CMSA Member Seminar \nSpeaker: Chuck Doran (Harvard CMSA) \nTitle: Modularity and Fibrations in Mirror Symmetry \nAbstract: We will introduce appearances of modularity in the study both of families of Calabi-Yau threefolds and of their enumerative invariants.  An important role is played by the structure of fibrations and the DHT fibration-degeneration mirror correspondence\, which clarifies how these notions of modularity are (and are not) related.  This is joint work with Boris Pioline and Thorsten Schimannek.
URL:https://cmsa.fas.harvard.edu/event/member-seminar-32224/
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-03.22.2024.png
END:VEVENT
END:VCALENDAR