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X-WR-CALDESC:Events for CMSA
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DTSTART;TZID=America/New_York:20220309T103000
DTEND;TZID=America/New_York:20220309T120000
DTSTAMP:20240301T070302Z
CREATED:20240214T105142Z
LAST-MODIFIED:20240301T070302Z
UID:10002682-1646821800-1646827200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Anomalies\, topological insulators and Kaehler-Dirac fermions
DESCRIPTION:Abstract: Motivated by a puzzle arising from recent work on staggered lattice fermions we introduce Kaehler-Dirac fermions and describe their connection both to Dirac fermions and staggered fermions. We show that they suffer from a gravitational anomaly that breaks a chiral U(1) symmetry specific to Kaehler-Dirac fermions down to Z_4 in any even dimension. In odd dimensions we show that the effective theory that results from integrating out massive Kaehler-Dirac fermions is a topological gravity theory. Such theories generalize Witten’s construction of (2+1) gravity as a Chern Simons theory. In the presence of a domain wall massless modes appear on the wall which can be consistently coupled to gravity due to anomaly inflow from the bulk gravitational theory. Much of this story parallels the usual discussion of topological insulators. The key difference is that the twisted chiral symmetry and anomaly structure of Kaehler-Dirac theories survives intact under discretization and governs the behavior of the lattice models. $Z_4$ invariant four fermion interactions can be used to gap out states in such theories without breaking symmetries and in flat space yields the known constraints on the number of Majorana fermions needed symmetric mass generation namely eight and sixteen Majorana spinors in two and four dimensions.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-9-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-03.09.2022-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220307T100000
DTEND;TZID=America/New_York:20220307T113000
DTSTAMP:20240301T073931Z
CREATED:20230730T175629Z
LAST-MODIFIED:20240301T073931Z
UID:10001144-1646647200-1646652600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:4d strings at strong coupling
DESCRIPTION:Speakers: Fernando Marchesano (UAM-CSIC\, Madrid)  and Max Wiesner (Harvard CMSA)\n\n\n\nTitle: 4d strings at strong coupling\n\n\nAs usual\, the format will be 45 min talk + 30 min discussion\, to encourage participation from the audience.\nLooking forward to seeing you there!
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-7-2022-swampland-seminar/
LOCATION:Virtual
CATEGORIES:Swampland Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220303T093000
DTEND;TZID=America/New_York:20220303T110000
DTSTAMP:20240813T163614Z
CREATED:20240214T105412Z
LAST-MODIFIED:20240813T163614Z
UID:10002684-1646299800-1646305200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Callan Rubakov Effect and Higher Charge Monopoles
DESCRIPTION:Abstract: In this talk we will discuss the interaction between magnetic monopoles and massless fermions. In the 1980’s Callan and Rubakov showed that in the simplest example and that fermion-monopole interactions catalyze proton decay in GUT completions of the standard model. Here we will explain how fermions in general representations interact with general spherically symmetric monopoles and classify the types of symmetries that are broken: global symmetries with ABJ-type anomalies.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-3-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-03.03.2022-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220302T140000
DTEND;TZID=America/New_York:20220302T150000
DTSTAMP:20240517T193649Z
CREATED:20230808T182233Z
LAST-MODIFIED:20240517T193649Z
UID:10001206-1646229600-1646233200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Scaling Laws and Their Implications for Coding AI
DESCRIPTION:Speaker: Jared Kaplan\, Johns Hopkins Dept. of Physics & Astronomy \nTitle: Scaling Laws and Their Implications for Coding AI \nAbstract:  Scaling laws and associated downstream trends can be used as an organizing principle when thinking about current and future ML progress.  I will briefly review scaling laws for generative models in a number of domains\, emphasizing language modeling.  Then I will discuss scaling results for transfer from natural language to code\, and results on python programming performance from “codex” and other models.  If there’s time I’ll discuss prospects for the future — limitations from dataset sizes\, and prospects for RL and other techniques.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/3-2-2022-new-technologies-in-mathematics-seminar/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/03.2.2022-1553x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220302T093000
DTEND;TZID=America/New_York:20220302T103000
DTSTAMP:20240222T171906Z
CREATED:20240214T040557Z
LAST-MODIFIED:20240222T171906Z
UID:10002521-1646213400-1646217000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Dimers and webs
DESCRIPTION:Speaker: Richard Kenyon (Yale) \nTitle: Dimers and webs \nAbstract: We consider SL_n-local systems on graphs on surfaces and show how the associated Kasteleyn matrix can be used to compute probabilities of various topological events involving the overlay of n independent dimer covers (or “n-webs”). \nThis is joint work with Dan Douglas and Haolin Shi.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/dimers-and-webs/
LOCATION:Virtual
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/02CMSA-Colloquium-03.02.2022.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220301T093000
DTEND;TZID=America/New_York:20220301T103000
DTSTAMP:20240304T083139Z
CREATED:20230825T075625Z
LAST-MODIFIED:20240304T083139Z
UID:10001291-1646127000-1646130600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Virtual localization for Artin stacks
DESCRIPTION:Abstract: This is a report about work in progress with: Adeel Khan\, Aloysha Latyntsev\, Hyeonjun Park and Charanya Ravi. We will describe a virtual Atiyah-Bott formula for Artin stacks.  In the Deligne-Mumford case our methods allow us to remove the global resolution hypothesis for the virtual normal bundle.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/virtual-localization-for-artin-stacks/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Algebraic-Geometry-in-String-Theory-02.22.2022-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220224T130000
DTEND;TZID=America/New_York:20220224T140000
DTSTAMP:20240304T051713Z
CREATED:20240214T080100Z
LAST-MODIFIED:20240304T051713Z
UID:10002576-1645707600-1645711200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Extreme Black Holes: Anabasis and Accidental Symmetry
DESCRIPTION:  \n \n  \nSpeaker: Achilleas Porfyriadis\, Harvard Black Hole Initiative \nTitle: Extreme Black Holes: Anabasis and Accidental Symmetry \nAbstract: The near-horizon region of black holes near extremality is universally AdS_2-like. In this talk I will concentrate on the simplest example of  AdS_2 x S^2 as the near-horizon of (near-)extreme Reissner-Nordstrom. I will first explain the SL(2)transformation properties of the spherically symmetric linear perturbations of  AdS_2 x S^2 and show how their backreaction leads to the Reissner-Nordstrom black hole. This backreaction with boundary condition change is called an anabasis. I will then show that the linear Einstein equation near AdS_2 x S^2\, with or without additional matter\, enjoys an accidental symmetry that may be thought of as an on-shell large diffeomorphism of AdS_2.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/2-24-2022-general-relativity-seminar/
LOCATION:Virtual
CATEGORIES:General Relativity Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220223T093000
DTEND;TZID=America/New_York:20220223T103000
DTSTAMP:20240501T204515Z
CREATED:20240214T040816Z
LAST-MODIFIED:20240501T204515Z
UID:10002522-1645608600-1645612200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Holographic Cone of Average Entropies and Universality of Black Holes
DESCRIPTION:Speaker: Bartek Czech\, Tsinghua University \nTitle: Holographic Cone of Average Entropies and Universality of Black Holes \nAbstract:  In the AdS/CFT correspondence\, the holographic entropy cone\, which identifies von Neumann entropies of CFT regions that are consistent with a semiclassical bulk dual\, is currently known only up to n=5 regions. I explain that average\nentropies of p-partite subsystems can be checked for consistency with a semiclassical bulk dual far more easily\, for an arbitrary number of regions n. This analysis defines the “Holographic Cone of Average\nEntropies” (HCAE). I conjecture the exact form of HCAE\, and find that it has the following properties: (1) HCAE is the simplest it could be\, namely it is a simplicial cone. (2) Its extremal rays represent stages of thermalization (black hole formation). (3) In a time-reversed picture\, the extremal rays of HCAE represent stages of unitary black hole evaporation\, as stipulated by the island solution of the black hole information paradox. (4) HCAE is bound by a novel\, infinite family of holographic entropy inequalities. (5) HCAE is the simplest it could be also in its dependence on the number of regions n\, namely its bounding inequalities are n-independent. (6) In a precise sense I describe\, the bounding inequalities of HCAE unify (almost) all previously discovered holographic inequalities and strongly constrain future inequalities yet to be discovered. I also sketch an interpretation of HCAE in terms of error correction and the holographic Renormalization Group. The big lesson that HCAE seems to be teaching us is about the universality of black hole physics.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/collloquium_22323/
LOCATION:Virtual
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220222T093000
DTEND;TZID=America/New_York:20220222T103000
DTSTAMP:20240304T083230Z
CREATED:20230825T075425Z
LAST-MODIFIED:20240304T083230Z
UID:10001290-1645522200-1645525800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Higgs-Coulomb correspondence in abelian GLSM
DESCRIPTION:Abstract: We construct a certain type of Gauged Linear Sigma Model quasimap invariants that generalize the original ones and are easier to compute. Higgs-Coulomb correspondence provides identification of generating functions of our invariants with certain analytic functions that can be represented as generalized inverse Mellin transforms. Analytic continuation of these functions provides wall-crossing results for GLSM and generalizes Landau- Ginzburg/Calabi-Yau correspondence. The talk is based on a joint work in progress with Melissa Liu.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/higgs-coulomb-correspondence-in-abelian-glsm/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Algebraic-Geometry-in-String-Theory-02.22.2022-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220217T093000
DTEND;TZID=America/New_York:20220217T110000
DTSTAMP:20240301T071849Z
CREATED:20240214T094917Z
LAST-MODIFIED:20240301T071849Z
UID:10002646-1645090200-1645095600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Spin-cobordisms\, surgeries and fermionic modular bootstrap
DESCRIPTION:Speaker: Andrea Grigoletto (SISSA & INFN) \nTitle: Spin-cobordisms\, surgeries and fermionic modular bootstrap \nAbstract: ‘tHooft anomalies of anomalous systems can be described via anomaly inflow by invertible theories living in one dimension higher. Thanks to this it is possible to provide a general method to determine modular transformations of anomalous 2d fermionic CFTs with general discrete symmetry group $G^f$. As a by-product\, one is able to determine explicit combinatorial expressions of spin-cobordism invariants in terms of Dehn-surgery representation of 3-manifolds. The same techniques also provide a method for evaluating the map from the group classifying free fermionic anomalies to the group of anomalies in interacting theories. As examples\, we work out the details for some symmetry groups\, including non-abelian ones\, and\, as an application\, we use these results to bootstrap the spectrum of the theories with a given anomaly.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/2-17-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-02.17.2022-1544x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220216T140000
DTEND;TZID=America/New_York:20220216T150000
DTSTAMP:20240515T205523Z
CREATED:20230808T181915Z
LAST-MODIFIED:20240515T205523Z
UID:10001205-1645020000-1645023600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Bootstrapping hyperbolic manifolds
DESCRIPTION:Speaker: James Bonifacio\, Cambridge DAMTP \nTitle: Bootstrapping hyperbolic manifolds \nAbstract: Hyperbolic manifolds are a class of Riemannian manifolds that are important in mathematics and physics\, playing a prominent role in topology\, number theory\, and string theory. Associated with a given hyperbolic metric is a sequence of numbers corresponding to the discrete eigenvalues of the Laplace-Beltrami operator. While these eigenvalues usually cannot be calculated exactly\, they can be found numerically and must also satisfy various bounds. In this talk\, I will discuss a new approach for finding numerical bounds on the eigenvalues of closed hyperbolic manifolds using general consistency conditions and semidefinite programming\, inspired by the approach of the conformal bootstrap from physics. Although these bootstrap bounds follow from seemingly trivial consistency conditions\, they are surprisingly strong and are sometimes almost saturated by actual manifolds; for example\, one such bound implies that the first nonzero eigenvalue of a closed hyperbolic surface must be less than 3.83890\, and this is very close to being saturated by a particular genus-2 surface called the Bolza surface. I will show how to derive this and other bounds and will discuss some possible future directions for this approach.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/2-16-2022-new-technologies-in-mathematics-seminar/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-02.16.2022-1553x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220216T103000
DTEND;TZID=America/New_York:20220216T120000
DTSTAMP:20240304T102225Z
CREATED:20240213T112617Z
LAST-MODIFIED:20240304T102225Z
UID:10002497-1645007400-1645012800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Topological Quantum Gravity and the Ricci Flow – Part I
DESCRIPTION:Speaker: Petr Hořava (UC Berkeley) \nTitle: Topological Quantum Gravity and the Ricci Flow – Part I \nAbstract: In this sequence of talks\, I will describe our work with Alexander Frenkel and Stephen Randall\, in which we presented a novel topological quantum gravity\, relating three previously unrelated fields:  Topological quantum field theories (of the cohomological type)\, the theory of Ricci flows on Riemannian manifolds\, and nonrelativistic quantum gravity.  The remarkable richness of results produced in the recent decades by mathematicians studying the Ricci flow promises to shed new light on the physics of the path integral in quantum gravity (at least in the topological regime).  In the opposite direction\, the techniques of quantum field theory and path integrals may end up putting some of the mathematical results in the Ricci flow theory in a new perspective as well.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-02.16.2022-1544x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220216T093000
DTEND;TZID=America/New_York:20220216T103000
DTSTAMP:20240425T182937Z
CREATED:20240213T112726Z
LAST-MODIFIED:20240425T182937Z
UID:10002499-1645003800-1645007400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Kobayashi-Hitchin correspondences for harmonic bundles and monopoles
DESCRIPTION:Speaker: Takuro Mochizuki (Kyoto University) \nTitle: Kobayashi-Hitchin correspondences for harmonic bundles and monopoles \nAbstract:  In 1960’s\, Narasimhan and Seshadri discovered the equivalence between irreducible unitary flat bundles and stable bundles of degree $0$ on compact Riemann surfaces. In 1980’s\, Donaldson\, Uhlenbeck and Yau generalized it to the equivalence between irreducible Hermitian-Einstein bundles and stable bundles on smooth projective varieties. This is a surprising bridge connecting differential geometry and algebraic geometry. Since then\, many interesting generalizations have been studied. \nIn this talk\, we would like to review a stream in the study of such correspondences for Higgs bundles\, integrable connections\, $D$-modules and periodic monopoles.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/2-16-2022-cmsa-colloquium/
LOCATION:Virtual
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-02.16.2022.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220215T093000
DTEND;TZID=America/New_York:20220215T103000
DTSTAMP:20240304T083319Z
CREATED:20230818T054001Z
LAST-MODIFIED:20240304T083319Z
UID:10001289-1644917400-1644921000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Virtual Coulomb branch and quantum K-theory
DESCRIPTION:Abstract: In this talk\, I will introduce a virtual variant of the quantized Coulomb branch constructed by Braverman-Finkelberg-Nakajima\, where the convolution product is modified by a virtual intersection. The resulting virtual Coulomb branch acts on the moduli space of quasimaps into the holomorphic symplectic quotient T^*N//G. When G is abelian\, over the torus fixed points\, this representation is a Verma module. The vertex function\, a K-theoretic enumerative invariant introduced by A. Okounkov\, can be expressed as a Whittaker function of the algebra. The construction also provides a description of the quantum q-difference module. As an application\, this gives a proof of the invariance of the quantum q-difference module under variation of GIT.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/virtual-coulomb-branch-and-quantum-k-theory/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220210T093000
DTEND;TZID=America/New_York:20220210T110000
DTSTAMP:20240301T072127Z
CREATED:20240214T100805Z
LAST-MODIFIED:20240301T072127Z
UID:10002658-1644485400-1644490800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:The global structure of the Standard Model and new nonperturbative processes
DESCRIPTION:Speaker: Mohamed Anber (Durham University) \nTitle: The global structure of the Standard Model and new nonperturbative processes \nAbstract: It is well-established that the Standard Model (SM) of particle physics is based on su(3)Xsu(2)Xu(1) Lie-algebra. What is less appreciated\, however\, is that SM accommodates a Z_6 1-form global symmetry.  Gauging this symmetry\, or a subgroup of it\, changes the global structure of the SM gauge group and amounts to summing over sectors of instantons with fractional topological charges. After a brief review of the concept of higher-form symmetries\, I will explain the origin of the Z_6 1-form symmetry and construct the explicit fractional-instanton solutions on compact manifolds. The new instantons mediate baryon-number and lepton-number violating processes\, which can win over the weak BPST-instanton processes\, provided that SM accommodates extra hyper-charged particles above the TeV scale. I will also comment on the cosmological aspects of the new solutions.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/2-10-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-02.10.2022-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220209T200000
DTEND;TZID=America/New_York:20220209T213000
DTSTAMP:20240301T072509Z
CREATED:20240214T103129Z
LAST-MODIFIED:20240301T072509Z
UID:10002674-1644436800-1644442200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:On the absence of global anomalies of heterotic string theories
DESCRIPTION:Speaker: Yuji Tachikawa (Kavli IPMU\, U Tokyo) \nTitle: On the absence of global anomalies of heterotic string theories \nAbstract: Superstring theory as we know it started from the discovery by Green and Schwarz in 1984 that the perturbative anomalies of heterotic strings miraculously cancel. But the cancellation of global anomalies of heterotic strings remained an open problem for a long time. \nIn this talk\, I would like to report how this issue was finally resolved last year\, by combining two developments outside of string theory. Namely\, on one hand\, the study of topological phases in condensed matter theory has led to our vastly improved understanding of the general form of global anomalies. On the other hand\, the study of topological modular forms in algebraic topology allows us to constrain the data of heterotic worldsheet theories greatly\, as far as their contributions to the anomalies are concerned. Putting them together\, it is possible to show that global anomalies of heterotic strings are always absent. \nThe talk is based on https://arxiv.org/abs/2103.12211 and https://arxiv.org/abs/2108.13542 \, in collaboration with Mayuko Yamashita.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/2-9-2022-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-02.09.2022-1544x2048-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220209T140000
DTEND;TZID=America/New_York:20220209T150000
DTSTAMP:20240517T193404Z
CREATED:20230808T181534Z
LAST-MODIFIED:20240517T193404Z
UID:10001204-1644415200-1644418800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Toward Demystifying Transformers and Attention
DESCRIPTION:Speaker: Ben Edelman\, Harvard Computer Science \nTitle: Toward Demystifying Transformers and Attention \nAbstract: Over the past several years\, attention mechanisms (primarily in the form of the Transformer architecture) have revolutionized deep learning\, leading to advances in natural language processing\, computer vision\, code synthesis\, protein structure prediction\, and beyond. Attention has a remarkable ability to enable the learning of long-range dependencies in diverse modalities of data. And yet\, there is at present limited principled understanding of the reasons for its success. In this talk\, I’ll explain how attention mechanisms and Transformers work\, and then I’ll share the results of a preliminary investigation into why they work so well. In particular\, I’ll discuss an inductive bias of attention that we call sparse variable creation: bounded-norm Transformer layers are capable of representing sparse Boolean functions\, with statistical generalization guarantees akin to sparse regression.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/2-9-2022-new-technologies-in-mathematics-seminar/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-02.09.2022-1553x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220208T213000
DTEND;TZID=America/New_York:20220208T223000
DTSTAMP:20240501T205116Z
CREATED:20240214T041520Z
LAST-MODIFIED:20240501T205116Z
UID:10002524-1644355800-1644359400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Tetrahedron instantons and M-theory indices
DESCRIPTION:Colloquium \nSpeaker: Wenbin Yan (Tsinghua University) \nTitle: Tetrahedron instantons and M-theory indices \nAbstract: We introduce and study tetrahedron instantons. Physically they capture instantons on $\mathbb{C}^{3}$ in the presence of the most general intersecting codimension-two supersymmetric defects. In this talk\, we will review instanton moduli spaces\, explain the construction\, moduli space and partition functions of tetrahedron instantons. We will also point out possible relations with M-theory index which could be a generalization of Gupakuma-Vafa theory.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/tetrahedron-instantons-and-m-theory-indices/
LOCATION:Virtual
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220208T093000
DTEND;TZID=America/New_York:20220208T103000
DTSTAMP:20240304T083416Z
CREATED:20230818T051427Z
LAST-MODIFIED:20240304T083416Z
UID:10001287-1644312600-1644316200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:SYZ Conjecture beyond Mirror Symmetry
DESCRIPTION:Abstract: Strominger-Yau-Zaslow conjecture is one of the guiding principles in mirror symmetry\, which not only predicts the geometric structures of Calabi-Yau manifolds but also provides a recipe for mirror construction. Besides mirror symmetry\, the SYZ conjecture itself is the holy grail in geometrical analysis and closely related to the behavior of the Ricci-flat metrics. In this talk\, we will explain how SYZ fibrations on log Calabi-Yau surfaces detect the non-standard semi-flat metric which generalized the semi-flat metrics of Greene-Shapere-Vafa-Yau. Furthermore\, we will use the SYZ fibration on log Calabi-Yau surfaces to prove the Torelli theorem of gravitational instantons of type ALH^*. This is based on the joint works with T. Collins and A. Jacob.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/syz-conjecture-beyond-mirror-symmetry/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220203T113000
DTEND;TZID=America/New_York:20220203T130000
DTSTAMP:20240301T073438Z
CREATED:20240301T073438Z
LAST-MODIFIED:20240301T073438Z
UID:10002886-1643887800-1643893200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Quantum Oscillations of Electrical Resistivity in an Insulator
DESCRIPTION:Speaker: Lu Li (U Michigan) \nTitle: Quantum Oscillations of Electrical Resistivity in an Insulator \nAbstract: In metals\, orbital motions of conduction electrons are quantized in magnetic fields\, which is manifested by quantum oscillations in electrical resistivity. This Landau quantization is generally absent in insulators\, in which all the electrons are localized. Here we report a notable exception in an insulator — ytterbium dodecaboride (YbB12). The resistivity of YbB12\, despite much larger than that of usual metals\, exhibits profound quantum oscillations under intense magnetic fields. This unconventional oscillation is shown to arise from the insulating bulk instead of conducting surface states. The large effective masses indicate strong correlation effects between electrons. Our result is the first discovery of quantum oscillations in the electrical resistivity of a strongly correlated insulator and will bring crucial insight into understanding the ground state in gapped Kondo systems.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/2-3-2022-quantum-matter-in-mathematics-and-physics-2/
LOCATION:Virtual
CATEGORIES:Quantum Matter
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220202T093000
DTEND;TZID=America/New_York:20220202T103000
DTSTAMP:20240304T075005Z
CREATED:20240214T041742Z
LAST-MODIFIED:20240304T075005Z
UID:10002525-1643794200-1643797800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Learning and inference from sensitive data
DESCRIPTION:Speaker: Adam Smith (Boston University) \nTitle: Learning and inference from sensitive data \nAbstract: Consider an agency holding a large database of sensitive personal information—say\,  medical records\, census survey answers\, web searches\, or genetic data. The agency would like to discover and publicly release global characteristics of the data while protecting the privacy of individuals’ records. \nI will discuss recent (and not-so-recent) results on this problem with a focus on the release of statistical models. I will first explain some of the fundamental limitations on the release of machine learning models—specifically\, why such models must sometimes memorize training data points nearly completely. On the more positive side\, I will present differential privacy\, a rigorous definition of privacy in statistical databases that is now widely studied\, and increasingly used to analyze and design deployed systems. I will explain some of the challenges of sound statistical inference based on differentially private statistics\, and lay out directions for future investigation.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/learning-and-inference-from-sensitive-data/
LOCATION:Virtual
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-02.02.2022.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220201T093000
DTEND;TZID=America/New_York:20220201T103000
DTSTAMP:20240304T064710Z
CREATED:20230818T053619Z
LAST-MODIFIED:20240304T064710Z
UID:10001288-1643707800-1643711400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Curve-counting with fixed domain (“Tevelev degrees”)
DESCRIPTION:Abstract: We will consider the following problem: if (C\,x_1\,…\,x_n) is a fixed general pointed curve\, and X is a fixed target variety with general points y_1\,…\,y_n\, then how many maps f:C -> X in a given homology class are there\, such that f(x_i)=y_i? When considered virtually in Gromov-Witten theory\, the answer may be expressed in terms of the quantum cohomology of X\, leading to explicit formulas in some cases (Buch-Pandharipande). The geometric question is more subtle\, though in the presence of sufficient positivity\, it is expected that the virtual answers are enumerative. I will give an overview of recent progress on various aspects of this problem\, including joint work with Farkas\, Pandharipande\, and Cela\, as well as work of other authors.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/curve-counting-with-fixed-domain-tevelev-degrees/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Algebraic-Geometry-in-String-Theory-02.01.2022-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20220106T090000
DTEND;TZID=America/New_York:20220106T100000
DTSTAMP:20240529T175141Z
CREATED:20240215T093525Z
LAST-MODIFIED:20240529T175141Z
UID:10002721-1641459600-1641463200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:The smooth closing lemma for area-preserving surface diffeomorphisms
DESCRIPTION:Speaker: Boyu Zhang\, Princeton University \nTitle: The smooth closing lemma for area-preserving surface diffeomorphisms \nAbstract: In this talk\, I will introduce the smooth closing lemma for area-preserving diffeomorphisms on surfaces. The proof is based on a Weyl formula for PFH spectral invariants and a non-vanishing result of twisted Seiberg- Witten Floer homology. This is joint work with Dan Cristofaro-Gardiner and Rohil Prasad.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/1-6-2022-interdisciplinary-science-seminar/
LOCATION:Virtual
CATEGORIES:Interdisciplinary Science Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Interdisciplinary-Science-Seminar-01.06.22.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211215T140000
DTEND;TZID=America/New_York:20211215T150000
DTSTAMP:20240515T204057Z
CREATED:20230808T180208Z
LAST-MODIFIED:20240515T204057Z
UID:10001202-1639576800-1639580400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Unreasonable effectiveness of the quantum complexity view on quantum many-body physics
DESCRIPTION:Speaker: Anurag Anshu\, Department of EECS & Challenge Institute for Quantum Computation\, UC Berkeley \nTitle: Unreasonable effectiveness of the quantum complexity view on quantum many-body physics \nAbstract: A central challenge in quantum many-body physics is to estimate the properties of natural quantum states\, such as the quantum ground states and Gibbs states. Quantum Hamiltonian complexity offers a computational perspective on this challenge and classifies these natural quantum states using the language of quantum complexity classes. This talk will provide a gentle introduction to the field and highlight its success in pinning down the hardness of a wide variety of quantum states. In particular\, we will consider the gapped ground states and Gibbs states on low dimensional lattices\, which are believed to exhibit ‘low complexity’ due to the widely studied area law behaviour. Here\, we will see the crucial role of complexity-theoretic methods in progress on the ‘area law conjecture’ and in the development of efficient algorithms to classically simulate quantum many-body systems.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-15-21-new-technologies-in-mathematics/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-12.15.21-2.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211209T093000
DTEND;TZID=America/New_York:20211209T143000
DTSTAMP:20250328T200233Z
CREATED:20230705T082223Z
LAST-MODIFIED:20250328T200233Z
UID:10000072-1639042200-1639060200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:CMSA Math-Science Literature Lecture - Karen Uhlenbeck
DESCRIPTION:Karen Uhlenbeck (Institute for Advanced Study) \nTitle: The Noether Theorems in Geometry: Then and Now \nAbstract: The 1918 Noether theorems were a product of the general search for energy and momentum conservation in Einstein’s newly formulated theory of general relativity. Although widely referred to as the connection between symmetry and conservation laws\, the theorems themselves are often not understood properly and hence have not been as widely used as they might be. In the first part of the talk\, I outline a brief history of the theorems\, explain a bit of the language\, translate the first theorem into coordinate invariant language and give a few examples. I will mention only briefly their importance in physics and integrable systems. In the second part of the talk\, I describe why they are still relevant in geometric analysis: how they underlie standard techniques and why George Daskalopoulos and I came to be interested in them for our investigation into the best Lipschitz maps of Bill Thurston. Some applications to integrals on a domain a hyperbolic surface leave open possibilities for applications to integrals on domains which are locally symmetric spaces of higher dimension. The talk finishes with an example or two from the literature. \nTalk Chair: Laura DeMarco \nVIDEO
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-9-21-math-science-literature-lecture-karen-uhlenbeck/
LOCATION:Virtual
CATEGORIES:Event,Math Science Literature Lecture Series,Public Lecture,Special Lectures
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/Lecture_Uhlenbeck_12921.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211208T140000
DTEND;TZID=America/New_York:20211208T150000
DTSTAMP:20240515T203917Z
CREATED:20230808T175752Z
LAST-MODIFIED:20240515T203917Z
UID:10001201-1638972000-1638975600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Hierarchical Transformers are More Efficient Language Models
DESCRIPTION:Speaker: Piotr Nawrot\, University of Warsaw \nTitle: Hierarchical Transformers are More Efficient Language Models \nAbstract: Transformer models yield impressive results on many NLP and sequence modeling tasks. Remarkably\, Transformers can handle long sequences which allows them to produce long coherent outputs: full paragraphs produced by GPT-3 or well-structured images produced by DALL-E. These large language models are impressive but also very inefficient and costly\, which limits their applications and accessibility. We postulate that having an explicit hierarchical architecture is the key to Transformers that efficiently handle long sequences. To verify this claim\, we first study different ways to upsample and downsample activations in Transformers so as to make them hierarchical. We use the best performing upsampling and downsampling layers to create Hourglass – a hierarchical Transformer language model. Hourglass improves upon the Transformer baseline given the same amount of computation and can yield the same results as Transformers more efficiently. In particular\, Hourglass sets new state-of-the-art for Transformer models on the ImageNet32 generation task and improves language modeling efficiency on the widely studied enwik8 benchmark.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-8-21-new-technologies-in-mathematics/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-12.08.21.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211208T103000
DTEND;TZID=America/New_York:20211208T120000
DTSTAMP:20240301T083428Z
CREATED:20240214T094451Z
LAST-MODIFIED:20240301T083428Z
UID:10002644-1638959400-1638964800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Defects\, link invariants and exact WKB
DESCRIPTION:Speaker: Fei Yan (Rutgers) \nTitle: Defects\, link invariants and exact WKB \nAbstract: I will describe some of my recent work on defects in supersymmetric field theories. The first part of my talk is focused on line defects in certain large classes of 4d N=2 theories and 3d N=2 theories. I will describe geometric methods to compute the ground states spectrum of the bulk-defect system\, as well as implications on the construction of link invariants. In the second part I will talk about some perspectives of surface defects in 4d N=2 theories and related applications on the exact WKB method for ordinary differential equations. This talk is based on past joint work with A. Neitzke\, various work in progress with D. Gaiotto\, S. Jeong\, A. Khan\, G. Moore\, as well as work by myself.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-8-2021-quantum-matter-in-mathematics-and-physics/
LOCATION:Virtual
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-12.08.21-1544x2048-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211207T093000
DTEND;TZID=America/New_York:20211207T103000
DTSTAMP:20240122T054102Z
CREATED:20230818T050741Z
LAST-MODIFIED:20240122T054102Z
UID:10001286-1638869400-1638873000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:2d N=(0\,1) gauge theories\, Spin(7) orientifolds and triality
DESCRIPTION:
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-7-21-algebraic-geometry-in-string-theory/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211201T140000
DTEND;TZID=America/New_York:20211201T143000
DTSTAMP:20240515T203641Z
CREATED:20230808T175251Z
LAST-MODIFIED:20240515T203641Z
UID:10001200-1638367200-1638369000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:The Principles of Deep Learning Theory
DESCRIPTION:Speaker: Dan Roberts\, MIT & Salesforce \nTitle: The Principles of Deep Learning Theory \nAbstract: Deep learning is an exciting approach to modern artificial intelligence based on artificial neural networks. The goal of this talk is to provide a blueprint — using tools from physics — for theoretically analyzing deep neural networks of practical relevance. This task will encompass both understanding the statistics of initialized deep networks and determining the training dynamics of such an ensemble when learning from data. \nIn terms of their “microscopic” definition\, deep neural networks are a flexible set of functions built out of many basic computational blocks called neurons\, with many neurons in parallel organized into sequential layers. Borrowing from the effective theory framework\, we will develop a perturbative 1/n expansion around the limit of an infinite number of neurons per layer and systematically integrate out the parameters of the network. We will explain how the network simplifies at large width and how the propagation of signals from layer to layer can be understood in terms of a Wilsonian renormalization group flow. This will make manifest that deep networks have a tuning problem\, analogous to criticality\, that needs to be solved in order to make them useful. Ultimately we will find a “macroscopic” description for wide and deep networks in terms of weakly-interacting statistical models\, with the strength of the interactions between the neurons growing with depth-to-width aspect ratio of the network. Time permitting\, we will explain how the interactions induce representation learning. \nThis talk is based on a book\, The Principles of Deep Learning Theory\, co-authored with Sho Yaida and based on research also in collaboration with Boris Hanin. It will be published next year by Cambridge University Press.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/12-1-21-new-technologies-in-mathematics-seminar-series/
LOCATION:Virtual
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-12.01.21.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20211130T093000
DTEND;TZID=America/New_York:20211130T103000
DTSTAMP:20240122T053703Z
CREATED:20230818T050118Z
LAST-MODIFIED:20240122T053703Z
UID:10001285-1638264600-1638268200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:K_2 and Quantum Curves
DESCRIPTION:
URL:https://live-hu-cmsa-222.pantheonsite.io/event/k_2-and-quantum-curves/
LOCATION:Virtual
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
END:VCALENDAR