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X-WR-CALDESC:Events for CMSA
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BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231011T140000
DTEND;TZID=America/New_York:20231011T150000
DTSTAMP:20240223T114336Z
CREATED:20240223T114336Z
LAST-MODIFIED:20240223T114336Z
UID:10002868-1697032800-1697036400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:LeanDojo: Theorem Proving with Retrieval-Augmented Language Models
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: Alex Gu\, MIT Dept. of EE&CS \nTitle: LeanDojo: Theorem Proving with Retrieval-Augmented Language Models \nAbstract: Large language models (LLMs) have shown promise in proving formal theorems using proof assistants such as Lean. However\, existing methods are difficult to reproduce or build on\, due to private code\, data\, and large compute requirements. This has created substantial barriers to research on machine learning methods for theorem proving. We introduce LeanDojo: an open-source Lean playground consisting of toolkits\, data\, models\, and benchmarks. LeanDojo extracts data from Lean and enables interaction with the proof environment programmatically. It contains fine-grained annotations of premises in proofs\, providing valuable data for premise selection: a key bottleneck in theorem proving. Using this data\, we develop ReProver (Retrieval-Augmented Prover): the first LLM-based prover that is augmented with retrieval for selecting premises from a vast math library. It is inexpensive and needs only one GPU week of training. Our retriever leverages LeanDojo’s program analysis capability to identify accessible premises and hard negative examples\, which makes retrieval much more effective. Furthermore\, we construct a new benchmark consisting of 96\,962 theorems and proofs extracted from Lean’s math library. It features a challenging data split requiring the prover to generalize to theorems relying on novel premises that are never used in training. We use this benchmark for training and evaluation\, and experimental results demonstrate the effectiveness of ReProver over non-retrieval baselines and GPT-4. We thus provide the first set of open-source LLM-based theorem provers without any proprietary datasets and release it under a permissive MIT license to facilitate further research. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/nt-101123-2/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-10.11.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231006T120000
DTEND;TZID=America/New_York:20231006T130000
DTSTAMP:20240223T105621Z
CREATED:20240223T105546Z
LAST-MODIFIED:20240223T105621Z
UID:10002854-1696593600-1696597200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Random matrices and large deviations 
DESCRIPTION:Member Seminar \nSpeaker: Benjamin McKenna \nTitle: Random matrices and large deviations \nAbstract: We give a generalist overview of random matrices and their (a)typical behaviors. In recent years\, classical results have been complemented by a variety of new ones\, in both the math and physics literatures\, whose proofs leverage connections with special integrals over matrix groups. Some of these models exhibit interesting transition points\, whose motivating relationships to eigenvector (de)localization are not yet fully understood. Based on joint work with Jonathan Husson. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-10623/
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:20231004T103000
DTEND;TZID=America/New_York:20231004T113000
DTSTAMP:20240221T111849Z
CREATED:20240221T111722Z
LAST-MODIFIED:20240221T111849Z
UID:10002779-1696415400-1696419000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Dipolar and modulated symmetry protected topological phases
DESCRIPTION:<strong>Topological Quantum Matter Seminar</strong> \n<strong>Speaker:</strong> Ho Tat Lam\, MIT \n<strong>Title:</strong> Dipolar and modulated symmetry protected topological phases \n<strong>Abstract:</strong> Modulated symmetries are symmetries whose symmetry generators exhibit spatial modulations. We will discuss one-dimensional symmetry protected topological (SPT) phases protected by modulated symmetries. We will present a simple recipe for constructing modulated SPT models by generalizing the concept of decorated domain walls. We will then focus on the simplest modulated SPT protected by dipolar symmetries\, classify them using matrix product states and construct their response field theories using twisted finite tensor gauge theories.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/tqms_10423/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Topological Quantum Matter Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Topological-Seminar-10.04.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231002T163000
DTEND;TZID=America/New_York:20231002T173000
DTSTAMP:20240227T095159Z
CREATED:20240227T095159Z
LAST-MODIFIED:20240227T095159Z
UID:10002874-1696264200-1696267800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Gravitational Instantons
DESCRIPTION:Speaker: Yu-Shen Lin (Boston University) \nTitle: Gravitational Instantons \nAbstract: Gravitational instantons were introduced by Hawking as building blocks of his Euclidean quantum gravity theory back in the 1970s. These are non-compact Calabi-Yau surfaces with L2 curvature and thus can be viewed as the non-compact analogue of K3 surfaces. K3 surfaces are 2-dimensional Calabi-Yau manifolds and are usually the testing stone before conquering the general Calabi-Yau problems. The moduli space of K3 surfaces and its compactification on their own form important problems in various branches in geometry. In this talk\, we will discuss the Torelli theorem of gravitational instantons\, how the cohomological invariants of a gravitational instanton determine them. As a consequence\, this leads to a description of the moduli space of gravitational instantons.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/colloquium-10223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-10.02.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20231002T103000
DTEND;TZID=America/New_York:20231002T113000
DTSTAMP:20240222T084421Z
CREATED:20240222T084421Z
LAST-MODIFIED:20240222T084421Z
UID:10002791-1696242600-1696246200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Motivic decomposition of moduli space from brane dynamics
DESCRIPTION:Algebraic Geometry in String Theory Seminar \n\n\nPre-talk Speaker: Kai Xu (CMSA): 10:00-10:30 am \n\nSpeaker: Kai Xu (CMSA) \nTitle: Motivic decomposition of moduli space from brane dynamics \nAbstract: Supersymmetric gauge theories encode deep structures in algebraic geometry\, and geometric engineering gives a powerful way to understand the underlying structures by string/M theory. In this talk we will see how the dynamics of M5 branes tell us about the motivic and semiorthogonal decompositions of moduli of bundles on curves.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/agst-10223/
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://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Algebraic-Geometry-in-String-Theory-10.02.2023.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230929T140000
DTEND;TZID=America/New_York:20230929T150000
DTSTAMP:20240223T103610Z
CREATED:20240223T103610Z
LAST-MODIFIED:20240223T103610Z
UID:10002848-1695996000-1695999600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Topological modular forms and heretoric string theory
DESCRIPTION:Special Seminar\n\n\n\n\n\nSpeaker: Mayuko Yamashita\, Kyoto University \n\nTitle: Topological modular forms and heretoric string theory \nAbstract: In this talk I will explain my works with Y. Tachikawa to study anomaly in heterotic string theory via homotopy theory\, especially the theory of Topological Modular Forms (TMF). TMF is an E-infinity ring spectrum which is conjectured by Stolz-Teichner to classify two-dimensional supersymmetric quantum field theories in physics. In the previous work (https://arxiv.org/abs/2108.13542)\, we proved the vanishing of anomalies in heterotic string theory mathematically by using TMF. \nFurthermore\, we have a recent update (https://arxiv.org/abs/2305.06196) on the previous work. Because of the vanishing result\, we can consider a secondary transformation of spectra\, which is shown to coincide with the Anderson self-duality morphism of TMF. This allows us to detect subtle torsion phenomena in TMF by differential-geometric ways\, and leads us to new conjectures on the relation between VOAs and TMF. \n\n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/ss_92923/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Special Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Special-Seminar-09.29.23-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230929T120000
DTEND;TZID=America/New_York:20230929T130000
DTSTAMP:20240223T112516Z
CREATED:20240223T112516Z
LAST-MODIFIED:20240223T112516Z
UID:10002863-1695988800-1695992400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Moduli of vector bundles on curve and semiorthogonal decomposition
DESCRIPTION:Member Seminar \nSpeaker: Kai Xu (CMSA) \nTitle: Moduli of vector bundles on curve and semiorthogonal decomposition \nAbstract: In this talk we construct semiorthogonal decompositions of moduli of vector bundles on a curve into its symmetric powers. The essential ingredients in the proof include Borel-Weil-Bott theory for loop groups\, derived Schur-Weyl duality for current groups and derived Θ-stratification. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-92923/
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:20230928T163000
DTEND;TZID=America/New_York:20230928T180000
DTSTAMP:20240813T161833Z
CREATED:20240221T112307Z
LAST-MODIFIED:20240813T161833Z
UID:10002780-1695918600-1695924000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Quantum field theory approach to quantum information
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Cenke Xu (UCSB) \nTitle: Quantum field theory approach to quantum information \nAbstract: We apply the formalism of quantum field theory and Euclidean space-time path integral to investigate a class of quantum information problems. In particular\, we investigate quantum many-body systems under weak-measurement and decoherence. The Euclidean space-time path integral allows us to map this problem to a quantum field theory with (temporal) boundary or defects. We therefore investigate two types of quantum many-body systems with nontrivial boundary physics: quantum critical points\, and states with nontrivial topology\, such as Chern insulator and symmetry protected topological states. For example\, we demonstrate that a Wilson-Fisher quantum critical point can be driven into an “extraordinary-log” phase after weak-measurement. Another example is that\, we argue that a system with higher form symmetry may be driven to a self-dual phase transition under weak measurement.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/qm_92823/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-09.28.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230928T130000
DTEND;TZID=America/New_York:20230928T140000
DTSTAMP:20240223T072654Z
CREATED:20240223T072654Z
LAST-MODIFIED:20240223T072654Z
UID:10002827-1695906000-1695909600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Strongly driven mixtures and membranes: Out of equilibrium surprises 
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Max Lavrentovich\, Worcester State University \nTitle: Strongly driven mixtures and membranes: Out of equilibrium surprises \nAbstract: The more prosaic cousin of active matter\, driven inactive matter\, is still full of unexpected phenomena. I will discuss two projects involving two seemingly mundane systems\, a phase-separating colloidal mixture and a lipid membrane\, which demonstrate counterintuitive properties when driven out of equilibrium. We will see that the phase separating mixture\, when driven by a uniform force\, develops (in simulations) an intriguing pattern with a characteristic length scale set by the magnitude of the drive. We will look at some theoretical approaches to understanding the pattern formation and possible experimental realizations. The membrane\, when driven by an oscillatory electric field\, develops (in experiments) a long-lived metastable state with a decreased capacitance and increased dissipation. This state may have implications for neuronal processing and memory formation.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/am-92823/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Active-Matter-Seminar-09.28.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230927T153000
DTEND;TZID=America/New_York:20230927T163000
DTSTAMP:20240223T112647Z
CREATED:20240223T112514Z
LAST-MODIFIED:20240223T112647Z
UID:10002862-1695828600-1695832200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Large deviations for the 3D dimer model
DESCRIPTION:Probability Seminar \nSpeaker: Catherine Wolfram (MIT) \nTitle: Large deviations for the 3D dimer model \nAbstract: A dimer tiling of Z^d is a collection of edges such that every vertex is covered exactly once. In 2000\, Cohn\, Kenyon\, and Propp showed that 2D dimer tilings satisfy a large deviations principle. In joint work with Nishant Chandgotia and Scott Sheffield\, we prove an analogous large deviations principle for dimers in 3D. A lot of the results for dimers in two dimensions use tools and exact formulas (e.g. the height function representation of a tiling or the Kasteleyn determinant formula) that are specific to dimension 2. In this talk\, I will try to give some intuition for why three dimensions is different from two\, explain how to formulate the large deviations principle in 3D\, show simulations\, and explain some of the ways that we use a smaller set of tools (e.g. Hall’s matching theorem or a double dimer swapping operation) in our arguments. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/probability-92723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Probability-Seminar-09.27.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230927T140000
DTEND;TZID=America/New_York:20230927T150000
DTSTAMP:20240227T082824Z
CREATED:20240227T082824Z
LAST-MODIFIED:20240227T082824Z
UID:10002872-1695823200-1695826800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Transformers for maths\, and maths for transformers
DESCRIPTION:New Technologies in Mathematics Seminar \nSpeaker: François Charton\, Meta AI \nTitle:  Transformers for maths\, and maths for transformers \nAbstract: Transformers can be trained to solve problems of mathematics. I present two recent applications\, in mathematics and physics: predicting integer sequences\, and discovering the properties of scattering amplitudes in a close relative of Quantum ChromoDynamics. \nProblems of mathematics can also help understand transformers. Using two examples from linear algebra and integer arithmetic\, I show that model predictions can be explained\, that trained models do not confabulate\, and that carefully choosing the training distributions can help achieve better\, and more robust\, performance. \n  \n  \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/nt-92723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:New Technologies in Mathematics Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-NTM-Seminar-09.27.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230925T100000
DTEND;TZID=America/New_York:20230925T113000
DTSTAMP:20240222T090151Z
CREATED:20240222T090151Z
LAST-MODIFIED:20240222T090151Z
UID:10002792-1695636000-1695641400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Species Scale across String Moduli Spaces
DESCRIPTION:Algebraic Geometry in String Theory Seminar \n\nPre-talk Speaker: David Wu (Harvard Physics): 10:00-10:30 am \nSpeaker: Damian van de Heisteeg\, CMSA \n\nTitle: Species Scale across String Moduli Spaces \nAbstract: String theories feature a wide array of moduli spaces. We propose that the energy cutoff scale of these theories – the so-called species scale – can be determined through higher-curvature corrections. This species scale varies with the moduli; we use it both asymptotically to bound the diameter of the field space\, as well as in the interior to determine a “desert point” where it is maximized.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/agst-92523/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Algebraic Geometry in String Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230922T100000
DTEND;TZID=America/New_York:20230922T113000
DTSTAMP:20240223T095601Z
CREATED:20240223T095601Z
LAST-MODIFIED:20240223T095601Z
UID:10002845-1695376800-1695382200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Floquet codes\, automorphisms\, and quantum computation
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Margarita Davydova (MIT) \nTitle: Floquet codes\, automorphisms\, and quantum computation \nAbstract: In this talk\, I will introduce a new kind of measurement-based quantum computation inspired by Floquet codes. In this model\, the quantum logical gates are implemented by short sequences of low-weight measurements which simultaneously encode logical information and enable error correction.  We introduce a new class of quantum error-correcting codes generalizing Floquet codes that achieve this\, which we call dynamic automorphism (DA) codes. \nAs in Floquet codes\, the instantaneous codespace of a DA code at any fixed point in time is that of a topological code. In this case\, the quantum computation can be viewed as a sequence of time-like domain walls implementing automorphisms of the topological order\, which can be understood in terms of reversible anyon condensation paths in a particular parent model.  This talk will introduce all of these concepts as well as provide a new perspective for thinking about Floquet codes. \nThe explicit examples that we construct\, which we call DA color codes\, can implement the full Clifford group of logical gates in 2+1d by two- and\, rarely three-body measurements. Using adaptive two-body measurements\, we can achieve a non-Clifford gate in 3+1d\, making the first step towards universal quantum computation in this model. \nThe talk is based on recent work with Nathanan Tantivasadakarn\, Shankar Balasubramanian\, and David Aasen [arxiv: 2307.10353].
URL:https://live-hu-cmsa-222.pantheonsite.io/event/qm_92223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-09.22.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230920T103000
DTEND;TZID=America/New_York:20230920T113000
DTSTAMP:20240223T104903Z
CREATED:20240223T104903Z
LAST-MODIFIED:20240223T104903Z
UID:10002851-1695205800-1695209400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Exact Results in Flat Band Hubbard Models
DESCRIPTION:Topological Quantum Matter Seminar \nSpeaker: Jonah Herzog-Arbeitman\, Princeton University \nTitle: Exact Results in Flat Band Hubbard Models \nAbstract: Flat bands\, like those in the kagome lattice or twisted bilayer graphene\, are a natural setting for studying strongly coupled physics since the interaction strength is the only energy scale in the problem. They can exhibit unconventional behavior in the multi-orbital case: the mean-field theory of flat band attractive Hubbard models shows the possibility of superconductivity even though the Fermi velocity of the bands is strictly zero. However\, it is not necessary to resort to this approximation. We demonstrate that the groundstates and low-energy excitations of a large class of attractive Hubbard models are exactly solvable\, offering a rare\, microscopic view of their physics. The solution reveals the importance of quantum geometry in escaping (some of) BCS phenomenology within a tractable and nontrivial strong coupling theory.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/tqms_92023/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Topological Quantum Matter Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Topological-Seminar-09.20.23.docx-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230915T120000
DTEND;TZID=America/New_York:20230915T130000
DTSTAMP:20240223T112851Z
CREATED:20240223T112851Z
LAST-MODIFIED:20240223T112851Z
UID:10002864-1694779200-1694782800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Quantum UV-IR map and curve counts in skeins
DESCRIPTION:Member Seminar \nSpeaker: Sunghyuk Park \nTitle: Quantum UV-IR map and curve counts in skeins \nAbstract: Quantum UV-IR map (a.k.a. q-nonabelianization map)\, introduced by Neitzke and Yan\, is a map from UV line defects in a 4d N=2 theory of class S to those of the IR. Mathematically\, it can be described as a map between skein modules and is a close cousin of quantum trace map of Bonahon and Wong. \nIn this talk\, I will discuss how quantum UV-IR map can be generalized to a map between HOMFLYPT skein modules\, using skein-valued curve counts of Ekholm and Shende.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-91523/
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:20230914T130000
DTEND;TZID=America/New_York:20230914T140000
DTSTAMP:20240223T111752Z
CREATED:20240223T111752Z
LAST-MODIFIED:20240223T111752Z
UID:10002860-1694696400-1694700000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Frustration-free states of cell fate networks: the case of the epithelial-mesenchymal transition
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Herbert Levine (Northeastern)\n\nTitle: Frustration-free states of cell fate networks: the case of the epithelial-mesenchymal transition\n\nAbstract: Cell fate decisions are made by allowing external signals to govern the steady-state pattern adopted by networks of interacting regulatory factors governing transcription and translation. One of these decisions\, of importance for both developmental processes and for cancer metastasis\, is the epithelial-mesenchymal transition (EMT). In this talk\, we will argue that these biological networks have highly non-generic interaction structures such that they allow for phenotypic states with very low frustration\, i.e. where most interactions are satisfied. This property has important consequences for the allowed dynamics of these systems.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/am-91423/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230913T163000
DTEND;TZID=America/New_York:20230913T180000
DTSTAMP:20240223T111403Z
CREATED:20240223T111403Z
LAST-MODIFIED:20240223T111403Z
UID:10002859-1694622600-1694628000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Anomalies of Non-Invertible Symmetries
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Clay Córdova (U Chicago) \nTitle: Anomalies of Non-Invertible Symmetries
URL:https://live-hu-cmsa-222.pantheonsite.io/event/qm_91323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-09.13.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230913T103000
DTEND;TZID=America/New_York:20230913T113000
DTSTAMP:20240223T113738Z
CREATED:20230904T061048Z
LAST-MODIFIED:20240223T113738Z
UID:10001122-1694601000-1694604600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Phase transitions out of quantum Hall states in moire TMD bilayers
DESCRIPTION:Topological Quantum Matter Seminar \nSpeaker: Xueyang Song (MIT) \nTitle: Phase transitions out of quantum Hall states in moire TMD bilayers \nAbstract: Motivated by the recent experimental breakthroughs in observing Fractional Quantum Anomalous Hall (FQAH) states in moir\’e Transition Metal Dichalcogenide (TMD) bilayers\, we propose and study various unconventional phase transitions between quantum Hall phases and Fermi liquids or charge ordered phases upon tuning the bandwidth.  At filling -2/3\, we describe a direct transition between the FQAH state and a Charge Density Wave (CDW) insulator. The critical theory resembles that of the familiar deconfined quantum critical point (DQCP) but with an additional Chern-Simons term. At filling -1/2\, we study the possibility of a continuous transition between the composite Fermi liquid (CFL) and the Fermi liquid (FL) building on and refining previous work by  Barkeshli and McGreevy.   Crucially we show that translation symmetry alone is enough to enable a second order CFL-FL transition. We argue that there must be critical CDW fluctuations though neither phase has long range CDW order.  A striking signature is a universal jump of resistivities at the critical point. With disorder\, we argue that the CDW order gets pinned and the CFL-FL evolution happens through an intermediate electrically insulating phase with mobile neutral fermions. A clean analog of this insulating phase with long range CDW order and a neutral fermi surface can potentially also exist.  We also present a critical theory for the CFL to FL transition at filling -3/4.  Our work opens up a new avenue to realize deconfined criticality and fractionalized phases beyond familiar Landau level physics in the moire Chern band system.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/tqms_91323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Topological Quantum Matter Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Topological-Seminar-09.12.23.docx-2.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230912T160000
DTEND;TZID=America/New_York:20230912T170000
DTSTAMP:20240223T104300Z
CREATED:20240223T104300Z
LAST-MODIFIED:20240223T104300Z
UID:10002849-1694534400-1694538000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Homotopy classes of loops of Clifford unitaries
DESCRIPTION:Topological Quantum Matter Seminar \nSpeaker: Roman Geiko\, UCLA \nTitle: Homotopy classes of loops of Clifford unitaries \nAbstract: We study Clifford locality-preserving unitaries and stabilizer Hamiltonians by means of Hermitian K-theory. We demonstrate how the notion of algebraic homotopy of modules over Laurent polynomial rings translates into the connectedness of two short-range entangled stabilizer Hamiltonians by a shallow Clifford circuit. We apply this observation to a classification of homotopy classes of loops of Clifford unitaries. The talk is based on a work in collaboration with Yichen Hu.  https://arxiv.org/abs/2306.09903.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/tqms_91223/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Topological Quantum Matter Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Topological-Seminar-09.12.23-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230908T100000
DTEND;TZID=America/New_York:20230908T113000
DTSTAMP:20240116T070515Z
CREATED:20230904T055802Z
LAST-MODIFIED:20240116T070515Z
UID:10001125-1694167200-1694172600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:A 6-year journey: from gravitational anomaly to a unified theory of generalized symmetry
DESCRIPTION:Quantum Matter Seminar \nSpeaker: Xiao-Gang Wen (MIT) \nTitle: A 6-year journey: from gravitational anomaly to a unified theory of generalized symmetry \nAbstract: Emergent symmetry can be generalized symmetry beyond (higher) group description and/or can be anomalous. I will describe a unified theory for generalized symmetry based on symmetry/topological-order correspondence. I will also discuss some applications of emergent generalized symmetry.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/qm_9823/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Quantum Matter
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-QMMP-09.08.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230516T090000
DTEND;TZID=America/New_York:20230519T170000
DTSTAMP:20231226T172026Z
CREATED:20230705T055549Z
LAST-MODIFIED:20231226T172026Z
UID:10000068-1684227600-1684515600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:GRAMSIA: Graphical Models\, Statistical Inference\, and Algorithms
DESCRIPTION:On May 16 – May 19\, 2023 the CMSA hosted a four-day workshop on GRAMSIA: Graphical Models\, Statistical Inference\, and Algorithms. The workshop was held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. This workshop was organized by David Gamarnik (MIT)\, Kavita Ramanan (Brown)\, and Prasad Tetali  (Carnegie Mellon). \nThe purpose of this workshop is to highlight various mathematical questions and issues associated with graphical models and message-passing algorithms\, and to bring together a group of researchers for discussion of the latest progress and challenges ahead. In addition to the substantial impact of graphical models on applied areas\, they are also connected to various branches of the mathematical sciences. Rather than focusing on the applications\, the primary goal is to highlight and deepen these mathematical connections. \nLocation: Room G10\, CMSA\, 20 Garden Street\, Cambridge MA 02138 \n  \nSpeakers:\n\nJake Abernethy (Georgia Tech)\nGuy Bresler (MIT)\nFlorent Krzakala (Ecole Polytechnique Federale de Lausanne)\nLester Mackey (Microsoft Research New England)\nTheo McKenzie (Harvard)\nAndrea Montanari (Stanford)\nElchanan Mossel (MIT)\nYury Polyanskiy (MIT)\nPatrick Rebeschini (Oxford)\nSubhabrata Sen (Harvard)\nDevavrat Shah (MIT)\nPragya Sur (Harvard)\nAlex Wein (UC Davis)\nYihong Wu (Yale)\nSarath Yasodharan (Brown)\nHorng-Tzer Yau (Harvard)\nChristina Lee Yu (Cornell)\nIlias Zadik (MIT)\n\nSchedule:\nTuesday\, May 16\, 2023 \n\n\n\n9:00 am\nBreakfast\n\n\n9:15 – 9:30 am\nIntroductory remarks by organizers\n\n\n9:30 – 10:20 am\nSubhabrata Sen (Harvard) \nTitle: Mean-field approximations for high-dimensional Bayesian regression \nAbstract: Variational approximations provide an attractive computational alternative to MCMC-based strategies for approximating the posterior distribution in Bayesian inference. The Naive Mean-Field (NMF) approximation is the simplest version of this strategy—this approach approximates the posterior in KL divergence by a product distribution. There has been considerable progress recently in understanding the accuracy of NMF under structural constraints such as sparsity\, but not much is known in the absence of such constraints. Moreover\, in some high-dimensional settings\, the NMF is expected to be grossly inaccurate\, and advanced mean-field techniques (e.g. Bethe approximation) are expected to provide accurate approximations. We will present some recent work in understanding this duality in the context of high-dimensional regression. This is based on joint work with Sumit Mukherjee (Columbia) and Jiaze Qiu (Harvard University).\n\n\n10:30 – 11:00 am\nCoffee break  \n\n\n11:00 – 11:50 am\nElchanan Mossel (MIT) \nTitle: Some modern perspectives on the Kesten-Stigum bound for reconstruction on trees. \nAbstract: The Kesten-Stigum bound is a fundamental spectral bound for reconstruction on trees. I will discuss some conjectures and recent progress on understanding when it is tight as well as some conjectures and recent progress on what it signifies even in cases where it is not tight.\n\n\n12:00 – 2:00 pm\nLunch\n\n\n2:00 – 2:50 pm\nChristina Lee Yu (Cornell) \nTitle: Exploiting Neighborhood Interference with Low Order Interactions under Unit Randomized Design \nAbstract: Network interference\, where the outcome of an individual is affected by the treatment assignment of those in their social network\, is pervasive in many real-world settings. However\, it poses a challenge to estimating causal effects. We consider the task of estimating the total treatment effect (TTE)\, or the difference between the average outcomes of the population when everyone is treated versus when no one is\, under network interference. Under a Bernoulli randomized design\, we utilize knowledge of the network structure to provide an unbiased estimator for the TTE when network interference effects are constrained to low order interactions among neighbors of an individual. We make no assumptions on the graph other than bounded degree\, allowing for well-connected networks that may not be easily clustered. Central to our contribution is a new framework for balancing between model flexibility and statistical complexity as captured by this low order interactions structure.\n\n\n3:00 – 3:30 pm\nCoffee break \n\n\n3:30 – 4:20 pm\nTheo McKenzie (Harvard) \nTitle: Spectral statistics for sparse random graphs \nAbstract: Understanding the eigenvectors and eigenvalues of the adjacency matrix of random graphs is fundamental to many algorithmic questions; moreover\, it is related to longstanding questions in quantum physics. In this talk we focus on random models of sparse graphs\, giving some properties that are unique to these sparse graphs\, as well as some specific obstacles. Based on this\, we show some new results on spectral statistics of sparse random graphs\, as well as some conjectures.\n\n\n4:40 – 6:30 pm\nLightning talk session + welcome reception\n\n\n\n  \nWednesday\, May 17\, 2023 \n\n\n\n9:00 am\nBreakfast\n\n\n9:30 – 10:20\nIlias Zadik (MIT) \nTitle: Revisiting Jerrum’s Metropolis Process for the Planted Clique Problem \nAbstract: Jerrum in 1992 (co-)introduced the planted clique model by proving the (worst-case initialization) failure of the Metropolis process to recover any o(sqrt(n))-sized clique planted in the Erdos-Renyi graph G(n\,1/2). This result is classically cited in the literature of the problem\, as the “first evidence” the o(sqrt(n))-sized planted clique recovery task is “algorithmically hard”.\nIn this work\, we show that the Metropolis process actually fails to work (under worst-case initialization) for any o(n)-sized planted clique\, that is the failure applies well beyond the sqrt(n) “conjectured algorithmic threshold”. Moreover we also prove\, for a large number of temperature values\, that the Metropolis process fails also under “natural initialization”\, resolving an open question posed by Jerrum in 1992.\n\n\n10:30 – 11:00\nCoffee break\n\n\n11:00 – 11:50\nFlorent Krzakala (Ecole Polytechnique Federale de Lausanne) \nTitle: Are Gaussian data all you need for machine learning theory? \nAbstract: Clearly\, no! Nevertheless\, the Gaussian assumption remains prevalent among theoreticians\, particularly in high-dimensional statistics and physics\, less so in traditional statistical learning circles. To what extent are Gaussian features merely a convenient choice for certain theoreticians\, or genuinely an effective model for learning? In this talk\, I will review recent progress on these questions\, achieved using rigorous probabilistic approaches in high-dimension and techniques from mathematical statistical physics. I will demonstrate that\, despite its apparent limitations\, the Gaussian approach is sometimes much closer to reality than one might expect. In particular\, I will discuss key findings from a series of recent papers that showcase the Gaussian equivalence of generative models\, the universality of Gaussian mixtures\, and the conditions under which a single Gaussian can characterize the error in high-dimensional estimation. These results illuminate the strengths and weaknesses of the Gaussian assumption\, shedding light on its applicability and limitations in the realm of theoretical statistical learning.\n\n\n12:00 – 2:00 pm\nLunch\n\n\n2:00 – 2:50 pm\nAndrea Montanari (Stanford) \nTitle: Dimension free ridge regression \nAbstract: Random matrix theory has become a widely useful tool in high-dimensional statistics and theoretical machine learning. However\, random matrix theory is largely focused on the proportional asymptotics in which the number of columns grows proportionally to the number of rows of the data matrix. This is not always the most natural setting in statistics where columns correspond to covariates and rows to samples. With the objective to move beyond the proportional asymptotics\, we revisit ridge regression. We allow the feature vector to be high-dimensional\, or even infinite-dimensional\, in which case it belongs to a separable Hilbert space and assume it to satisfy a certain convex concentration property. Within this setting\, we establish non-asymptotic bounds that approximate the bias and variance of ridge regression in terms of the bias and variance of an ‘equivalent’ sequence model (a regression model with diagonal design matrix). Previously\, such an approximation result was known only in the proportional regime and only up to additive errors: in particular\, it did not allow to characterize the behavior of the excess risk when this converges to 0. Our general theory recovers earlier results in the proportional regime (with better error rates). As a new application\, we obtain a completely explicit and sharp characterization of ridge regression for Hilbert covariates with regularly varying spectrum. Finally\, we analyze the overparametrized near-interpolation setting and obtain sharp ‘benign overfitting’ guarantees. \n[Based on joint work with Chen Cheng]\n\n\n3:00 – 3:50 pm\nYury Polyanskiy (MIT) \nTitle: Recent results on broadcasting on trees and stochastic block model \nAbstract: I will survey recent results and open questions regarding the q-ary stochastic block model and its local version (broadcasting on trees\, or BOT). For example\, establishing uniqueness of non-trivial solution to distribution recursions (BP fixed point) implies a characterization for the limiting mutual information between the graph and community labels. For q=2 uniqueness holds in all regimes. For q>2 uniqueness is currently only proved above a certain threshold that is asymptotically (for large q) is close to Kesten-Stigum (KS) threshold. At the same time between the BOT reconstruction and KS we show that uniqueness does not hold\, at least in the presence of (arbitrary small) vertex-level side information. I will also discuss extension of the robust reconstruction result of Janson-Mossel’2004. \nBased on joint works with Qian Yu (Princeton) and Yuzhou Gu (MIT).\n\n\n4:00 – 4:30 pm\nCoffee break \n\n\n4:30 – 5:20 pm\nAlex Wein (UC Davis) \nTitle: Is Planted Coloring Easier than Planted Clique? \nAbstract: The task of finding a planted clique in the random graph G(n\,1/2) is perhaps the canonical example of a statistical-computational gap: for some clique sizes\, the task is statistically possible but believed to be computationally hard. Really\, there are multiple well-studied tasks related to the planted clique model: detection\, recovery\, and refutation. While these are equally difficult in the case of planted clique\, this need not be true in general. In the related planted coloring model\, I will discuss the computational complexity of these three tasks and the interplay among them. Our computational hardness results are based on the low-degree polynomial model of computation.By taking the complement of the graph\, the planted coloring model is analogous to the planted clique model but with many planted cliques. Here our conclusion is that adding more cliques makes the detection problem easier but not the recovery problem.\n\n\n\n  \nThursday\, May 18\, 2023 \n\n\n\n9:00\nBreakfast\n\n\n9:30 – 10:20\nGuy Bresler (MIT) \nTitle: Algorithmic Decorrelation and Planted Clique in Dependent Random Graphs \nAbstract: There is a growing collection of average-case reductions starting from Planted Clique (or Planted Dense Subgraph) and mapping to a variety of statistics problems\, sharply characterizing their computational phase transitions. These reductions transform an instance of Planted Clique\, a highly structured problem with its simple clique signal and independent noise\, to problems with richer structure. In this talk we aim to make progress in the other direction: to what extent can these problems\, which often have complicated dependent noise\, be transformed back to Planted Clique? Such a bidirectional reduction between Planted Clique and another problem shows a strong computational equivalence between the two problems.  We develop a new general framework for reasoning about the validity of average-case reductions based on low sensitivity to perturbations. As a concrete instance of our general result\, we consider the planted clique (or dense subgraph) problem in an ambient graph that has dependent edges induced by randomly adding triangles to the Erdos-Renyi graph G(n\,p)\, and show how to successfully eliminate dependence by carefully removing the triangles while approximately preserving the clique (or dense subgraph). Joint work with Chenghao Guo and Yury Polyanskiy.\n\n\n10:30 – 11:00\nCoffee break  \n\n\n11:00 – 11:50\nSarath Yasodharan (Brown) \nTitle: A Sanov-type theorem for unimodular marked random graphs and its applications \nAbstract: We prove a Sanov-type large deviation principle for the component empirical measures of certain sequences of unimodular random graphs (including Erdos-Renyi and random regular graphs) whose vertices are marked with i.i.d. random variables. Specifically\, we show that the rate function can be expressed in a fairly tractable form involving suitable relative entropy functionals. As a corollary\, we establish a variational formula for the annealed pressure (or limiting log partition function) for various statistical physics models on sparse random graphs. This is joint work with I-Hsun Chen and Kavita Ramanan.\n\n\n12:00 – 12:15 pm \n12:15 – 2:00 pm\nGroup Photo  \nLunch \n\n\n2:00 – 2:50 pm\nPatrick Rebeschini (Oxford) \nTitle: Implicit regularization via uniform convergence \nAbstract: Uniform convergence is one of the main tools to analyze the complexity of learning algorithms based on explicit regularization\, but it has shown limited applicability in the context of implicit regularization. In this talk\, we investigate the statistical guarantees on the excess risk achieved by early-stopped mirror descent run on the unregularized empirical risk with the squared loss for linear models and kernel methods. We establish a direct link between the potential-based analysis of mirror descent from optimization theory and uniform learning. This link allows characterizing the statistical performance of the path traced by mirror descent directly in terms of localized Rademacher complexities of function classes depending on the choice of the mirror map\, initialization point\, step size\, and the number of iterations. We will discuss other results along the way.\n\n\n3:00 – 3:50 pm\nPragya Sur (Harvard) \nTitle: A New Central Limit Theorem for the Augmented IPW estimator in high dimensions \nAbstract: Estimating the average treatment effect (ATE) is a central problem in causal inference. Modern advances in the field studied estimation and inference for the ATE in high dimensions through a variety of approaches. Doubly robust estimators such as the augmented inverse probability weighting (AIPW) form a popular approach in this context. However\, the high-dimensional literature surrounding these estimators relies on sparsity conditions\, either on the outcome regression (OR) or the propensity score (PS) model. This talk will introduce a new central limit theorem for the classical AIPW estimator\, that applies agnostic to such sparsity-type assumptions. Specifically\, we will study properties of the cross-fit version of the estimator under well-specified OR and PS models\, and the proportional asymptotics regime where the number of confounders and sample size diverge proportional to each other. Under assumptions on the covariate distribution\, our CLT will uncover two crucial phenomena among others: (i) the cross-fit AIPW exhibits a substantial variance inflation that can be quantified in terms of the signal-to-noise ratio and other problem parameters\, (ii) the asymptotic covariance between the estimators used while cross-fitting is non-negligible even on the root-n scale. These findings are strikingly different from their classical counterparts\, and open a vista of possibilities for studying similar other high-dimensional effects. On the technical front\, our work utilizes a novel interplay between three distinct tools—approximate message passing theory\, the theory of deterministic equivalents\, and the leave-one-out approach.\n\n\n4:00 – 4:30 pm\nCoffee break \n\n\n4:30 – 5:20 pm\nYihong Wu (Yale) \nTitle: Random graph matching at Otter’s threshold via counting chandeliers\n\nAbstract: We propose an efficient algorithm for graph matching based on similarity scores constructed from counting a certain family of weighted trees rooted at each vertex. For two Erdős–Rényi graphs G(n\,q) whose edges are correlated through a latent vertex correspondence\, we show that this algorithm correctly matches all but a vanishing fraction of the vertices with high probability\, provided that nq\to\infty and the edge correlation coefficient ρ satisfies ρ^2>α≈0.338\, where α is Otter’s tree-counting constant. Moreover\, this almost exact matching can be made exact under an extra condition that is information-theoretically necessary. This is the first polynomial-time graph matching algorithm that succeeds at an explicit constant correlation and applies to both sparse and dense graphs. In comparison\, previous methods either require ρ=1−o(1) or are restricted to sparse graphs. The crux of the algorithm is a carefully curated family of rooted trees called chandeliers\, which allows effective extraction of the graph correlation from the counts of the same tree while suppressing the undesirable correlation between those of different trees. This is joint work with Cheng Mao\, Jiaming Xu\, and Sophie Yu\, available at https://arxiv.org/abs/2209.12313\n\n\n\n  \nFriday\, May 19\, 2023 \n\n\n\n9:00\nBreakfast\n\n\n9:30 – 10:20\nJake Abernethy (Georgia Tech) \nTitle: Optimization\, Learning\, and Margin-maximization via Playing Games \nAbstract: A very popular trick for solving certain types of optimization problems is this: write your objective as the solution of a two-player zero-sum game\, endow both players with an appropriate learning algorithm\, watch how the opponents compete\, and extract an (approximate) solution from the actions/decisions taken by the players throughout the process. This approach is very generic and provides a natural template to produce new and interesting algorithms. I will describe this framework and show how it applies in several scenarios\, including optimization\, learning\, and margin-maximiation problems. Along the way we will encounter a number of novel tools and rediscover some classical ones as well.\n\n\n10:30 – 11:00\nCoffee break  \n\n\n11:00 – 11:50\nDevavrat Shah (MIT) \nTitle: On counterfactual inference with unobserved confounding via exponential family \nAbstract: We are interested in the problem of unit-level counterfactual inference with unobserved confounders owing to the increasing importance of personalized decision-making in many domains: consider a recommender system interacting with a user over time where each user is provided recommendations based on observed demographics\, prior engagement levels as well as certain unobserved factors. The system adapts its recommendations sequentially and differently for each user. Ideally\, at each point in time\, the system wants to infer each user’s unknown engagement if it were exposed to a different sequence of recommendations while everything else remained unchanged. This task is challenging since: (a) the unobserved factors could give rise to spurious associations\, (b) the users could be heterogeneous\, and (c) only a single trajectory per user is available. \nWe model the underlying joint distribution through an exponential family. This reduces the task of unit-level counterfactual inference to simultaneously learning a collection of distributions of a given exponential family with different unknown parameters with single observation per distribution. We discuss a computationally efficient method for learning all of these parameters with estimation error scaling linearly with the metric entropy of the space of unknown parameters – if the parameters are an s-sparse linear combination of k known vectors in p dimension\, the error scales as O(s log k/p).  En route\, we derive sufficient conditions for compactly supported distributions to satisfy the logarithmic Sobolev inequality. \nBased on a joint work with Raaz Dwivedi\, Abhin Shah and Greg Wornell (all at MIT) with manuscript available here: https://arxiv.org/abs/2211.08209\n\n\n12:00 – 2:00 pm\nLunch  \n\n\n2:00 – 2:50 pm\nLester Mackey  (Microsoft Research New England) \nTitle: Advances in Distribution Compression \nAbstract: This talk will introduce two new tools for summarizing a probability distribution more effectively than independent sampling or standard Markov chain Monte Carlo thinning:\n1. Given an initial n-point summary (for example\, from independent sampling or a Markov chain)\, kernel thinning finds a subset of only square-root n-points with comparable worst-case integration error across a reproducing kernel Hilbert space.\n2. If the initial summary suffers from biases due to off-target sampling\, tempering\, or burn-in\, Stein thinning simultaneously compresses the summary and improves the accuracy by correcting for these biases.\nThese tools are especially well-suited for tasks that incur substantial downstream computation costs per summary point like organ and tissue modeling in which each simulation consumes 1000s of CPU hours.\nBased on joint work with Raaz Dwivedi\, Marina Riabiz\, Wilson Ye Chen\, Jon Cockayne\, Pawel Swietach\, Steven A. Niederer\, Chris. J. Oates\, Abhishek Shetty\, and Carles Domingo-Enrich.\n\n\n3:00 – 3:30 pm\nCoffee break \n\n\n3:30 – 4:20 pm\nHorng-Tzer Yau (Harvard) \nTitle: On the spectral gap of mean-field spin glass models. \nAbstract: We will discuss recent progress regarding spectral gaps for the Glauber dynamics of spin glasses at high temperature. In addition\, we will also report on estimating the operator norm  of the covariance matrix for the SK model.\n\n\n\n  \nModerators: Benjamin McKenna\, Harvard CMSA & Changji Xu\, Harvard CMSA \n\n  \n \nCMSA COVID-19 Policies
URL:https://live-hu-cmsa-222.pantheonsite.io/event/gramsia2023/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/jpeg:https://live-hu-cmsa-222.pantheonsite.io/media/GRAMSIAcover-600x338-1.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230515T120000
DTEND;TZID=America/New_York:20230515T130000
DTSTAMP:20240216T105142Z
CREATED:20230817T172120Z
LAST-MODIFIED:20240216T105142Z
UID:10001245-1684152000-1684155600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Quantum information and extended topological quantum field theory 
DESCRIPTION:Member Seminar \nSpeaker: Gabriel Wong \nTitle: Quantum information and extended topological quantum field theory \nAbstract: Recently\, ideas from quantum information theory have played an important role in condensed matter and quantum gravity research. Most of these applications focus on the entanglement structure of quantum states\, and the computation of entanglement measures such as entanglement entropy has been an essential part of the story. In this talk\, we will address some subtleties that arise when trying to define entanglement entropy in quantum field theory and quantum gravity. In particular\, we will explain why extended topological field theory provides a useful framework to define and compute entanglement entropy in a continuous system. Time permitting\, we will explain some recent applications of these ideas in low dimensional quantum gravity and to topological string theory. \n  \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-51523/
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:20230507T090000
DTEND;TZID=America/New_York:20230512T180000
DTSTAMP:20240215T100004Z
CREATED:20230705T055311Z
LAST-MODIFIED:20240215T100004Z
UID:10000069-1683450000-1683914400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Workshop on Global Categorical Symmetries
DESCRIPTION:The CMSA will be hosting a Workshop on Global Categorical Symmetries from May 7 – 12\, 2023 \nParticipation in the workshop is by invitation. \nPublic Lectures \nThere will be three lectures on Thursday\, May 11\, 2023\, which are open to the public.\nLocation:  Room G-10\, CMSA\, 20 Garden Street\, Cambridge MA 02138\nNote: The public lectures will be held in-person only. \n2:00 – 2:50 pm\nSpeaker: Kantaro Ohmori (U Tokyo )\nTitle: Fusion Surface Models: 2+1d Lattice Models from Higher Categories\nAbstract: Generalized symmetry in general dimensions is expected to be described by higher categories. Conversely\, one might expect that\, given a higher category with appropriate structures\, there exist models that admit the category as its symmetry. In this talk I will explain a construction of such 2+1d lattice models for fusion 2-categories defined by Douglas and Reutter\, generalizing the work of Aasen\, Fendley and Mong on anyon chains. The construction is by decorating a boundary of a topological Freed-Teleman-Moore sandwich into a non-topological boundary. In particular we can construct a family of candidate lattice systems for chiral topological orders. \n  \n3:00 – 3:50 pm\nSpeaker: David Jordan (Edinburgh)\nTitle: Langlands duality for 3-manifolds\nAbstract: Originating in number theory\, and permeating representation theory\, algebraic geometry\, and quantum field theory\, Langlands duality is a pattern of predictions relating pairs of mathematical objects which have no clear a priori mathematical relation. In this talk I’ll explain a new conjectural appearance of Langlands duality in the setting of 3-manifold topology\, I’ll give some evidence in the form of special cases\, and I’ll survey how the conjecture relates to both the arithmetic and geometric Langlands duality conjectures. \n3:50 – 4:30 pm\nTea/Snack Break \n4:30 – 5:30 pm\nSpeaker: Ken Intriligator (UCSD)\nColloquium\nTitle: QFT Aspects of Symmetry\nAbstract: Everything in the Universe\, including the photons that we see and the quarks and electrons in our bodies\, are actually ripples of quantum fields. Quantum field theory (QFT) is the underlying mathematical framework of Nature\, and in the case of electrons and photons it is the most precisely tested theory in science. Strongly coupled aspects\, e.g. the confinement of quarks and gluons at long distances\, remain challenging. QFT also describes condensed matter systems\, connects to string theory and quantum gravity\, and describes cosmology. Symmetry has deep and powerful realizations and implications throughout physics\, and this is especially so for the study of QFT. Symmetries play a helpful role in characterizing the phases of theories and their behavior under renormalization group flows (zooming out). Quantum field theory has also been an idea generating machine for mathematics\, and there has been increasingly fruitful synergy in both directions. We are currently exploring the symmetry-based interconnections between QFT and mathematics in our Simons Collaboration on Global Categorical Symmetry\, which is meeting here this week. I will try to provide an accessible\, colloquium-level introduction to aspects of symmetries and QFT\, both old and new.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/globalcomputing23/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Workshop
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230504T093000
DTEND;TZID=America/New_York:20230504T103000
DTSTAMP:20240228T073615Z
CREATED:20230818T044217Z
LAST-MODIFIED:20240228T073615Z
UID:10001263-1683192600-1683196200@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Testing GR with GWs
DESCRIPTION:General Relativity Seminar \nSpeaker: Vitor Cardoso\, IST\, Lisbon and The Niels Bohr Institute\, Copenhagen \nTitle: Testing GR with GWs \nAbstract: One of the most remarkable possibilities of General Relativity concerns gravitational collapse to black holes\, leaving behind a geometry with light rings\, ergoregions and horizons. These peculiarities are responsible for uniqueness properties and energy extraction mechanisms that turn black holes into ideal laboratories of strong gravity\, of particle physics (yes!) and of possible quantum-gravity effects. I will discuss some of the latest progress in tests of General Relativity with black holes.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/gr_5423/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:General Relativity Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-GR-Seminar-05.04.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230503T153000
DTEND;TZID=America/New_York:20230503T163000
DTSTAMP:20240111T083748Z
CREATED:20230808T175916Z
LAST-MODIFIED:20240111T083748Z
UID:10001198-1683127800-1683131400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Random Neural Networks
DESCRIPTION:Probability Seminar \nSpeaker: Boris Hanin (Princeton)\n\nTitle: Random Neural Networks \nAbstract: Fully connected neural networks are described two by structural parameters: a depth L and a width N. In this talk\, I will present results and open questions about the asymptotic analysis of such networks with random weights and biases in the regime where N (and potentially L) are large. The first set of results are for deep linear networks\, which are simply products of L random matrices of size N x N. I’ll explain how the setting where the ratio L / N is fixed with both N and L large reveals a number of phenomena not present when only one of them is large. I will then state several results about non-linear networks in which this depth-to-width ratio L / N again plays a crucial role and gives an effective notion of depth for a random neural network.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/probability-5323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Probability-Seminar-05.03.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230503T123000
DTEND;TZID=America/New_York:20230503T133000
DTSTAMP:20240216T085646Z
CREATED:20230817T183740Z
LAST-MODIFIED:20240216T085646Z
UID:10001284-1683117000-1683120600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Generative Adversarial Networks (GANs): An Analytical Perspective
DESCRIPTION:Speaker: Xin Guo\, UC Berkeley \nTitle: Generative Adversarial Networks (GANs): An Analytical Perspective \nAbstract: Generative models have attracted intense interests recently. In this talk\, I will discuss one class of generative models\, Generative Adversarial Networks (GANs).  I will first provide a gentle review of the mathematical framework behind GANs. I will then proceed to discuss a few challenges in GANs training from an analytical perspective. I will finally report some recent progress for GANs training in terms of its stability and convergence analysis. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/collquium-5323/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-05.03.2023.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230502T120000
DTEND;TZID=America/New_York:20230502T130000
DTSTAMP:20240118T085308Z
CREATED:20230817T171918Z
LAST-MODIFIED:20240118T085308Z
UID:10001244-1683028800-1683032400@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Toroidal Positive Mass Theorem
DESCRIPTION:Member Seminar \nSpeaker: Aghil Alaee \nTitle: Toroidal Positive Mass Theorem \nAbstract: In this talk\, we review the positive mass conjecture in general relativity and prove a toroidal version of this conjecture in an asymptotically hyperbolic setting.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/member-seminar-5223/
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:20230427T130000
DTEND;TZID=America/New_York:20230427T140000
DTSTAMP:20240209T052245Z
CREATED:20230824T183024Z
LAST-MODIFIED:20240209T052245Z
UID:10001810-1682600400-1682604000@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Competition at the front of expanding populations
DESCRIPTION:Active Matter Seminar\n\n\nSpeaker: Mehran Kardar\, MIT \nTitle: Competition at the front of expanding populations \nAbstract: When competing species grow into new territory\, the population is dominated by descendants of successful ancestors at the expansion front. Successful ancestry depends on the reproductive advantage (fitness)\, as well as ability and opportunity to colonize new domains. (1) Based on symmetry considerations\, we present a model that  integrates both elements by coupling the classic description of one-dimensional competition (Fisher equation) to the minimal model of front shape (KPZ equation). Macroscopic manifestations of these equations on growth morphology are explored\, providing a framework to study spatial competition\, fixation\, and differentiation\, In particular\, we find that ability to expand in space may overcome reproductive advantage in colonizing new territory. (2) Variations of fitness\, as well as fixation time upon differentiation\, are shown to belong to distinct universality classes depending on limits to gain of fitness.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/am-42723/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Active Matter Seminar
ATTACH;FMTTYPE=:
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230426T153000
DTEND;TZID=America/New_York:20230426T163000
DTSTAMP:20240111T083026Z
CREATED:20230808T175545Z
LAST-MODIFIED:20240111T083026Z
UID:10001197-1682523000-1682526600@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Boundary current fluctuations for the half space ASEP
DESCRIPTION:Probability Seminar \nSpeaker: Jimmy He (MIT) \nTitle: Boundary current fluctuations for the half space ASEP \nAbstract: The half space asymmetric simple exclusion process (ASEP) is an interacting particle system on the half line\, with particles allowed to enter/exit at the boundary. I will discuss recent work on understanding fluctuations for the number of particles in the half space ASEP started with no particles\, which exhibits the Baik-Rains phase transition between GSE\, GOE\, and Gaussian fluctuations as the boundary rates vary. As part of the proof\, we find new distributional identities relating this system to two other models\, the half space Hall-Littlewood process\, and the free boundary Schur process\, which allows exact formulas to be computed.
URL:https://live-hu-cmsa-222.pantheonsite.io/event/probability-42623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Probability Seminar
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Probability-Seminar-04.26.23.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20230426T123000
DTEND;TZID=America/New_York:20230426T133000
DTSTAMP:20240122T053311Z
CREATED:20230817T183259Z
LAST-MODIFIED:20240122T053311Z
UID:10001283-1682512200-1682515800@live-hu-cmsa-222.pantheonsite.io
SUMMARY:Boundary behavior at classical and quantum phase transitions
DESCRIPTION:Speaker: Max Metlitski (MIT) \nTitle: Boundary behavior at classical and quantum phase transitions \nAbstract: There has been a lot of recent interest in the boundary behavior of materials. This interest is driven in part by the field of topological states of quantum matter\, where exotic protected boundary states are ubiquitous. In this talk\, I’ll ask: what happens at a boundary of a system\, when the bulk goes through a phase transition. While this question was studied in the context of classical statistical mechanics in the 70s and 80s\, basic aspects of the boundary phase diagram for the simplest classical phase transitions have been missed until recently. I’ll describe progress in this field\, as well as some extensions to quantum phase transitions. \n 
URL:https://live-hu-cmsa-222.pantheonsite.io/event/collquium-42623/
LOCATION:CMSA Room G10\, CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://live-hu-cmsa-222.pantheonsite.io/media/CMSA-Colloquium-04.26.2023.rev2_.png
END:VEVENT
END:VCALENDAR