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DTSTART;TZID=America/New_York:20191101T090000
DTEND;TZID=America/New_York:20191101T170000
DTSTAMP:20260430T092023
CREATED:20230715T072841Z
LAST-MODIFIED:20250305T211543Z
UID:10000122-1572598800-1572627600@cmsa.fas.harvard.edu
SUMMARY:Learning from health data in the million genome era
DESCRIPTION:On November 1\, 2019 the CMSA will be hosting a conference organized by Seven Bridges Genomics. The workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nProjects currently underway around the world are collecting detailed health and genomic data from millions of volunteers. In parallel\, numerous healthcare systems have announced commitments to integrate genomic data into the standard of care for select patients. These data have the potential to reveal transformative insights into health and disease. However\, to realize this promise\, novel approaches are required across the full life cycle of data analysis. This symposium will include discussion of advanced statistical and algorithmic approaches to draw insights from petabyte scale genomic and health data; success stories to date; and a view towards the future of clinical integration of genomics in the learning health system. \nSpeakers:  \n\nHeidi Rehm\, Ph.D.\nChief Genomics Officer\, MGH; Professor of Pathology\, MGH\, BWH & Harvard Medical School; Medical Director\, Broad Institute Clinical Research Sequencing Platform.\nSaiju Pyarajan\, Ph.D.\nDirector\, Centre for Data and Computational Sciences\,VABHS\, and Department of Medicine\, BWH and HMS\nTianxi Cai\, Sci.D\nJohn Rock Professor of Population and Translational Data Sciences\, Department of Biostatistics\, Harvard School of Public Health\nSusan Redline\, M.D.\, M.P.H\nFarrell Professor of Sleep MedicineHarvard Medical School\, Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center\nAvinash Sahu\, Ph.D.\nPostdoctoral Research Fellow\, Dana Farber Cancer Institute\, Harvard School of Public Health\nPeter J. Park\, Ph.D.\nProfessor of Biomedical Informatics\, Department of Biomedical Informatics\, Harvard Medical School\nDavid Roberson\nCommunity Engagement Manager\, Seven Bridges
URL:https://cmsa.fas.harvard.edu/event/learning-from-health-data-in-the-million-genome-era/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Conference,Event
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/SEVENB0051-POSTER-Harvard-Seminar-REV1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191030T163000
DTEND;TZID=America/New_York:20191030T173000
DTSTAMP:20260430T092023
CREATED:20240212T111504Z
LAST-MODIFIED:20240514T174927Z
UID:10002049-1572453000-1572456600@cmsa.fas.harvard.edu
SUMMARY:Spacetime\, Quantum Mechanics and Positive Geometry at Infinity
DESCRIPTION:Speaker: Nima Arkani-Hamed (IAS)\n\nTitle: Spacetime\, Quantum Mechanics and Positive Geometry at Infinity\n 
URL:https://cmsa.fas.harvard.edu/event/10-30-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-10.30.19-791x1024-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191028T090000
DTEND;TZID=America/New_York:20191030T170000
DTSTAMP:20260430T092023
CREATED:20230715T071637Z
LAST-MODIFIED:20250327T144000Z
UID:10000121-1572253200-1572454800@cmsa.fas.harvard.edu
SUMMARY:Spacetime and Quantum Mechanics Master Class Workshop
DESCRIPTION:As part of the program on Spacetime and Quantum Mechanics\, Total Positivity and Motives\, the CMSA will host a “Master Class Workshop”  on October 28-30\, 2019. Each day of the workshop will feature an intensive full day of pedagogical lectures\, with the aim of bringing actively interested but non-expert physicists and mathematicians up to speed on the featured topics. \nEveryone is welcome to attend the lectures. \nThe master class workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nOrganizers: \n\nNima Arkani-Hamed (IAS)\nLauren Williams (Harvard)\nAlex Postnikov (MIT)\nThomas Lam (Michigan)\n\n\nHere is a partial list of the mathematicians and physicists who have indicated that they will attend part or all of this special program as a visitor: \n\nPaolo Benincasa\, 11/17/2019 – 11/29/2019\nJacob Bourjaily\, 9/1/2019 – 12/15/2019\nFrancis Brown\, 9/15/2019 – 9/20/2019\nSimon Caron-Huot\, 9/30/2019 – 10/04/2019\nLance Dixon\, 9/9/2019 – 9/20/2019\nCharles Doran\, 10/19/2019 – 11/1/2019\nJames Drummond\, 10/14/2019 – 10/18/2019\nNick Early\, 11/18/2019 – 11/22/2019\nLivia Ferro\, 10/27/2019 – 11/9/2019\nSergey Fomin\, 10/6/2019 – 10/16/2019\nSebastian Franco\, 10/9/2019 – 10/19/2019\nHadleigh Frost\, 9/15/2019 – 12/20/2019\nMichael Green\, 10/05/2019 – 10/13/2019\nAlexander Goncharov\, 12/05/2019 – 12/20/2019\nSong He\, 9/29/2019 – 11/10/2019\nXuhua He\, 10/30/2019-11/03/2019.\nEnrico Herrmann\, 10/27/2019 – 11/9/2019\nYutin Huang\, 9/30/2019 – 10/12/2019\nSteven Karp\, 10/11/2019 – 11/03/2019\nTomasz Lukowski\, 10/27/2019 – 11/11/2019\nAndrew McLeod\, 10/6/2019 – 10/19/2019 & 11/3/2019 – 11/16/2019\nSebastian Mizera\, 10/28/2019 – 11/1/2019\nErik Panzer\, 9/15/2019 – 9/25/2019\nMatteo Parisi\, 10/26/2019 – 11/10/2019\nJulio Parra-Martinez\, 10/10/2019 – 05/12/2019\n Pierpaolo Mastrolia\, 11/8/2019 – 11/16/2019\nPasha Pylyavskyy\, 9/8/2019 – 9/22/2019 & 10/14/2019 – 11/1/2019\nJunjie Rao\, 10/25/2019 – 11/04/2019\nGiulio Salvatori\, 9/3/2019 – 12/15/2019\nMichael Shapiro\, 10/27/2019 – 11/2/2019\nDavid Speyer\, 10/14/2019 – 10/18/2019\nHugh Thomas\, 10/27/2019 – 11/22/2019\nJaroslav Trnka\, 9/30/2019 – 10/04/2019\, 10/28/2019 – 11/01/2019\, 11/18/2019 – 11/22/2019\nCristian Vergu\, 11/10/2019 – 11/30/2019\nMatthias Volk\, 10/14/2019 – 10/25/2019\nMatthew von Hippel\, 11/11/2019 – 11/22/2019\nPierre Vanhove\, 10/22/2019 – 10/31/2019\nMatthias Wilhelm\, 10/14/2019 – 10/25/2019
URL:https://cmsa.fas.harvard.edu/event/spacetime-and-quantum-mechanics-master-class-workshop/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Space-Time-poster-5.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191022T121100
DTEND;TZID=America/New_York:20191022T121100
DTSTAMP:20260430T092023
CREATED:20230707T175654Z
LAST-MODIFIED:20250328T185250Z
UID:10000120-1571746260-1571746260@cmsa.fas.harvard.edu
SUMMARY:2019 Ding Shum Lecture
DESCRIPTION:  \nOn October 22\, 2019\, the CMSA held the third annual Ding Shum lecture. \nSpeaker: Ronald L. Rivest (MIT) \nTitle: Election Security \nRonald L. Rivest is an Institute Professor at the Massachusetts Institute of Technology. He is a member of the Electrical Engineering and Computer Science Department and the Computer Science and Artificial Intelligence Laboratory (CSAIL) and a founder of the Cryptography and Information Security research group within CSAIL. His research has been in the areas of algorithms\, machine learning\, cryptography\, and election security\, for which he has received multiple awards\, including: the ACM Turing Award (with Adleman and Shamir)\, the BBVA Frontiers of Knowledge Award\, National Inventor’s Hall of Fame membership\, and the Marconi Prize. \nProf. Rivest is also well-known as a co-author of the textbook “Introduction to Algorithms” (with Cormen\, Leiserson\, and Stein)\, and as a co-inventor of the RSA public-key cryptosystem (with Adleman and Shamir). He is a co-founder of RSA and of Verisign.He has served on the Technical Guidelines Development Committee (advisory to the Election Assistance Commission)\, in charge of the Security subcommittee. He is a member of the CalTech/MIT Voting Technology Project\, on the Board of Verified Voting\, and an advisor to the Electronic Privacy Information Center. Additionally\, he has served on the Technical Guidelines Development Committee (advisory to the Election Assistance Commission)\, as a member of the CalTech/MIT Voting Technology Project\, and as an advisor to the Electronic Privacy Information Center. \n  \n \nLast year featured Eric Maskin\, who spoke on “How to Improve Presidential Elections: the Mathematics of Voting.” The first Ding Shum lecture took place on October 10\, 2017\, featuring Leslie Valiant on “Learning as a Theory of Everything.” \nThis event is made possible by the generous funding of Ding Lei and Harry Shum.\n 
URL:https://cmsa.fas.harvard.edu/event/2019-ding-shum-lecture/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Ding Shum Lecture,Event,Public Lecture,Special Lectures
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/DingShum-2019-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191016T160000
DTEND;TZID=America/New_York:20191016T170000
DTSTAMP:20260430T092023
CREATED:20240212T103628Z
LAST-MODIFIED:20240514T175134Z
UID:10001994-1571241600-1571245200@cmsa.fas.harvard.edu
SUMMARY:Monogamy of entanglement and convex geometry
DESCRIPTION:Speaker: Aram Harrow (MIT)\n\n\nTitle: Monogamy of entanglement and convex geometry\nAbstract: The SoS (sum of squares) hierarchy is a flexible algorithm that can be used to optimize polynomials and to test whether a quantum state is entangled or separable.  (Remarkably\, these two problems are nearly isomorphic.)  These questions lie at the boundary of P\, NP and the unique games conjecture\, but it is in general open how well the SoS algorithm performs.   I will discuss how ideas from quantum information (the “monogamy” property of entanglement) can be used to understand this algorithm.  Then I will describe an alternate algorithm that relies on apparently different tools from convex geometry that achieves similar performance.  This is an example of a series of remarkable parallels between SoS algorithms and simpler algorithms that exhaustively search over carefully chosen sets.  Finally\, I will describe known limitations on SoS algorithms for these problems.\n  \n 
URL:https://cmsa.fas.harvard.edu/event/10-16-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-10.16.19-791x1024-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191016T121900
DTEND;TZID=America/New_York:20191018T121900
DTSTAMP:20260430T092023
CREATED:20230707T175143Z
LAST-MODIFIED:20250328T144653Z
UID:10000119-1571228340-1571401140@cmsa.fas.harvard.edu
SUMMARY:Noncommutative Analysis\, Computational Complexity\, and Quantum Information
DESCRIPTION:On October 16-18\, 2019 the CMSA hosted a workshop on Noncommutative Analysis\, Computational Complexity\, and Quantum Information. \nThis workshop focuses on linking three different rapidly developing areas: noncommutative real algebraic geometry (RAG)\, theory of computation and quantum information theory. This mix of overlapping but independently developing topics should lead to a stimulating flow of tools and important problems into several disciplines.  Given the different communities there will be an emphasis on tutorials and making the lectures broadly understandable. \nThe workshop was held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nOrganizers: Boaz Barak\, Bill Helton\, Pablo Parrilo\, & Tselil Schramm. \nSpeakers:\n\nJason Altschuler\, MIT | Video\nBoaz Barak\, Harvard | Video\nAnkit Garg\, Microsoft Research | Slides | Video\nDavid Gosset\, University of Waterloo | Video\nAram Harrow\, MIT | Video\nIgor Klep\, University of Ljubljana\nSalma Kuhlmann\, Universität Konstanz | Video\nScott McCullough\, University of Florida | Slides\nIon Nechita\, Laboratoire de Physique Théorique | Slides | Video\nRafael Oliveira\, University of Toronto | Video\nVern Paulsen\, University of Waterloo | Video\nSuvrit Sra\, MIT | Video\nVictor Vinnikov\, Ben Gurion University | Video\nJurij Volčič\, Texas A&M University | Slides | Video\nAdam Bene Watts\, MIT
URL:https://cmsa.fas.harvard.edu/event/noncommutative-analysis-computational-complexity-and-quantum-information-2/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Noncommutative-Analysis-Poster-3.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20191002T163000
DTEND;TZID=America/New_York:20191002T173000
DTSTAMP:20260430T092023
CREATED:20240212T101431Z
LAST-MODIFIED:20240530T194159Z
UID:10001965-1570033800-1570037400@cmsa.fas.harvard.edu
SUMMARY:Cohomologies on almost complex manifolds and their applications 
DESCRIPTION:Speaker: Spiro Karigiannis (University of Waterloo)\n\n\nTitle: Cohomologies on almost complex manifolds and their applications\n\nAbstract: We define three cohomologies on an almost complex manifold (M\, J)\, defined using the Nijenhuis-Lie derivations induced from the almost complex structure J and its Nijenhuis tensor N\, regarded as vector-valued forms on M. One of these can be applied to distinguish non-isomorphic non-integrable almost complex structures on M. Another one\, the J-cohomology\, is familiar in the integrable case but we extend its definition and applicability to the case of non-integrable almost complex structures. The J-cohomology encodes whether a complex manifold satisfies the “del-delbar-lemma”\, and more generally in the non-integrable case the J-cohomology encodes whether (M\, J) satisfies a generalization of this lemma. We also mention some other potential cohomologies on almost complex manifolds\, related to an interesting question involving the Nijenhuis tensor. This is joint work with Ki Fung Chan and Chi Cheuk Tsang.
URL:https://cmsa.fas.harvard.edu/event/10-2-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-10.02.19-791x1024-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190925T163000
DTEND;TZID=America/New_York:20190925T173000
DTSTAMP:20260430T092023
CREATED:20240212T104035Z
LAST-MODIFIED:20240514T175737Z
UID:10001999-1569429000-1569432600@cmsa.fas.harvard.edu
SUMMARY:Double affine Hecke algebras
DESCRIPTION:Speaker: Pavel Etingof (MIT)\n\nTitle:  Double affine Hecke algebras\n\nAbstract: Double affine Hecke algebras (DAHAs) were introduced by I. Cherednik in the early 1990s to prove Macdonald’s conjectures. A DAHA is the quotient of the group algebra of the elliptic braid group attached to a root system by Hecke relations. DAHAs and their degenerations are now central objects of representation theory. They also have numerous connections to many other fields — integrable systems\, quantum groups\, knot theory\, algebraic geometry\, combinatorics\, and others. In my talk\, I will discuss the basic properties of double affine Hecke algebras and touch upon some applications.\n\n\n\n  \n 
URL:https://cmsa.fas.harvard.edu/event/9-25-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-09.25.19-791x1024-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190918T163000
DTEND;TZID=America/New_York:20190918T173000
DTSTAMP:20260430T092023
CREATED:20240212T102253Z
LAST-MODIFIED:20240514T175908Z
UID:10001976-1568824200-1568827800@cmsa.fas.harvard.edu
SUMMARY:A taste of noncommutative convex algebraic geometry
DESCRIPTION:Speaker: Bill Helton (UC San Diego)\n\nTitle:  A taste of noncommutative convex algebraic geometry\n\nAbstract: The last decade has seen the development of a substantial noncommutative (in a free algebra) real and complex algebraic geometry. The aim of the subject is to develop a systematic theory of equations and inequalities for (noncommutative) polynomials or rational functions of matrix variables. Such issues occur in linear systems engineering problems\, in free probability (random matrices)\, and in quantum information theory. In many ways the noncommutative (NC) theory is much cleaner than classical (real) algebraic geometry. For example\,\n\n◦ A NC polynomial\, whose value is positive semidefinite whenever you plug matrices into it\, is a sum of squares of NC polynomials.\n◦ A convex NC semialgebraic set has a linear matrix inequality representation.\n◦ The natural Nullstellensatz are falling into place.\n\n The goal of the talk is to give a taste of a few basic results and some idea of how these noncommutative problems occur in engineering. The subject is just beginning and so is accessible without much background. Much of the work is joint with Igor Klep who is also visiting CMSA for the Fall of 2019.
URL:https://cmsa.fas.harvard.edu/event/9-18-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-09.12.19-791x1024-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190910T091500
DTEND;TZID=America/New_York:20190911T152500
DTSTAMP:20260430T092023
CREATED:20230707T174623Z
LAST-MODIFIED:20250328T144415Z
UID:10000118-1568106900-1568215500@cmsa.fas.harvard.edu
SUMMARY:Topology and Dynamics in Quantum Matter Workshop
DESCRIPTION:On September 10-11\, 2019\, the CMSA  hosted a second workshop on Topological Aspects of Condensed Matter. \nNew ideas rooted in topology have recently had a major impact on condensed matter physics\, and have led to new connections with high energy physics\, mathematics and quantum information theory.  The aim of this program will be to deepen these connections and spark new progress by fostering discussion and new collaborations within and across disciplines. \nTopics include i) the classification of topological states  ii) topological orders in two and three dimensions including quantum spin liquids\, quantum Hall states and fracton phases and iii)  interplay of symmetry and topology in quantum many body systems\, including symmetry protected topological phases\, symmetry fractionalization and anomalies iv) topological phenomena in quantum systems  driven far from equlibrium v) quantum field theory approaches to topological matter. \nThis workshop is part of the CMSA’s program on Program on Topological Aspects of Condensed Matter\, and is the second of two workshops\, in addition to a visitor program and seminars. \nThe workshop was held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \nOrganizers: Michael Hermele (CU Boulder) and Ashvin Vishwanath (Harvard) \nPartial list of speakers:\n\nNima Arkani-Hamed\, IAS\nJennifer Cano\, Stony Brook\nMeng Cheng\, Yale\nLukasz Fidkowski\, UW Seattle\nDaniel Freed\, Texas\nJeongwan Haah\, Microsoft Research\nAnton Kapustin\, Caltech\nZohar Komargodski\, SCGP/Stony Brook\nJohn McGreevy\, UC San Diego\nPrineha Narang\, Harvard\nYing Ran\, Boston College\nShinsei Ryu\, Chicago\nCumrun Vafa\, Harvard\nChong Wang\, Perimeter\nZhenghan Wang\, Microsoft Station Q\n\n 
URL:https://cmsa.fas.harvard.edu/event/topology-and-dynamics-in-quantum-matter-workshop-2/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Topology-Poster.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190901T090000
DTEND;TZID=America/New_York:20191220T170000
DTSTAMP:20260430T092023
CREATED:20230904T082838Z
LAST-MODIFIED:20250327T185837Z
UID:10000007-1567328400-1576861200@cmsa.fas.harvard.edu
SUMMARY:Spacetime and quantum mechanics\, total positivity and motives
DESCRIPTION:Recent developments have poised this area to make serious advances in 2019\, and we feel that bringing together many of the relevant experts for an intensive semester of discussions and collaboration will trigger some great things to happen. To this end\, the organizers will host a small workshop during Fall 2019\, with between 20-30 participants. They will also invite 10-20 longer-term visitors throughout the semester. Additionally\, there will be a seminar held weekly on Thursdays at 2:30pm in CMSA G10. \nOrganizers: \n\nNima Arkani-Hamed (IAS)\nLauren Williams (Harvard)\nAlexander Postnikov (MIT)\nThomas Lam (Michigan)\n\n. \nWorkshops: \n \n  \nSpacetime and Quantum Mechanics Workshop\, October 28-30\, 2019\n\n\nHere is a partial list of the mathematicians and physicists who have indicated that they will attend part or all of this special program as a visitor: \n\nPaolo Benincasa\, 11/17/2019 – 11/29/2019\nJacob Bourjaily\, 9/1/2019 – 12/15/2019\nFrancis Brown\, 9/15/2019 – 9/20/2019\nSimon Caron-Huot\, 9/30/2019 – 10/04/2019\nLance Dixon\, 9/9/2019 – 9/20/2019\nCharles Doran\, 10/19/2019 – 11/1/2019\nJames Drummond\, 10/14/2019 – 10/18/2019\nNick Early\, 11/18/2019 – 11/22/2019\nLivia Ferro\, 10/27/2019 – 11/9/2019\nSergey Fomin\, 10/6/2019 – 10/16/2019\nSebastian Franco\, 10/9/2019 – 10/19/2019\nHadleigh Frost\, 9/15/2019 – 12/20/2019\nMichael Green\, 10/05/2019 – 10/13/2019\nAlexander Goncharov\, 12/05/2019 – 12/20/2019\nSong He\, 9/29/2019 – 11/10/2019\nXuhua He\, 10/30/2019-11/03/2019\nEnrico Herrmann\, 10/27/2019 – 11/9/2019\nYutin Huang\, 9/30/2019 – 10/12/2019\nSteven Karp\, 10/11/2019 – 11/03/2019\nTomasz Lukowski\, 10/27/2019 – 11/11/2019\nAndrew McLeod\, 10/6/2019 – 10/19/2019 & 11/3/2019 – 11/16/2019\nSebastian Mizera\, 10/28/2019 – 11/1/2019\nErik Panzer\, 9/15/2019 – 9/25/2019\nMatteo Parisi\, 10/26/2019 – 11/10/2019\nJulio Parra-Martinez\, 10/10/2019 – 05/12/2019\n Pierpaolo Mastrolia\, 11/8/2019 – 11/16/2019\nPasha Pylyavskyy\, 9/8/2019 – 9/22/2019 & 10/14/2019 – 11/1/2019\nJunjie Rao\, 10/25/2019 – 11/04/2019\nGiulio Salvatori\, 9/3/2019 – 12/15/2019\nMichael Shapiro\, 10/27/2019 – 11/2/2019\nDavid Speyer\, 10/14/2019 – 10/18/2019\nHugh Thomas\, 10/27/2019 – 11/22/2019\nJaroslav Trnka\, 9/30/2019 – 10/04/2019\, 10/28/2019 – 11/01/2019\, 11/18/2019 – 11/22/2019\nCristian Vergu\, 11/10/2019 – 11/30/2019\nMatthias Volk\, 10/14/2019 – 10/25/2019\nMatthew von Hippel\, 11/11/2019 – 11/22/2019\nPierre Vanhove\, 10/22/2019 – 10/31/2019\nMatthias Wilhelm\, 10/14/2019 – 10/25/2019
URL:https://cmsa.fas.harvard.edu/event/spacetime-and-quantum-mechanics-total-positivity-and-motives/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Programs
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190829T083000
DTEND;TZID=America/New_York:20190831T144500
DTSTAMP:20260430T092023
CREATED:20230707T174207Z
LAST-MODIFIED:20250328T144206Z
UID:10000117-1567067400-1567262700@cmsa.fas.harvard.edu
SUMMARY:Workshop on Foundations of Computational Science
DESCRIPTION:On August 29-31\, 2019 the Center of Mathematical Sciences and Applications  hosted a workshop on Foundations of Computational Science. The workshop was held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA.  This workshop was organized by David Xianfeng Gu. \nSpeakers: \n\nSarah Adel Bargal\, Boston University\nJianfeng Chen\, Harvard\nTat Seng Chua\, National University of Singapore\nKe Deng\, Tsinghua\nDavid Xianfeng Gu\, Stony Brook\nYike Guo\, Imperial College London\nMinlie Huang\, Tsinghua\nScott Kominers\, Harvard\nBrian Kulis\, Boston University\nWee Sun Lee\, National University of Singapore\nQianxiao Li\, National University of Singapore\nHanzhong Liu\, Tsinghua\nJun Liu\, Harvard\nXiao-Li Meng\, Harvard\nCengiz Pehlevan\, Harvard\nDonald Rubin\, Harvard\nSuproteem Sarkar\, Harvard\nZuowei Shen\, National University of Singapore\nYuanchun Shi\, Tsinghua\nJustin Solomon\, MIT\nHang Su\, Tsinghua\nMaosong Sun\, Tsinghua\nMirac Suzgun\, Harvard\nSergiy Verstyuk\, CMSA\nXiaoqin Wang\, Tsinghua\nBin Xu\, Tsinghua\nJun Zhu\, Tsinghua\nWenwu Zhu\, Tsinghua
URL:https://cmsa.fas.harvard.edu/event/workshop-on-foundations-of-computational-science/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/AI-Poster-3.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190819T083000
DTEND;TZID=America/New_York:20190820T164000
DTSTAMP:20260430T092023
CREATED:20230707T174003Z
LAST-MODIFIED:20250328T145128Z
UID:10000116-1566203400-1566319200@cmsa.fas.harvard.edu
SUMMARY:2019 Big Data Conference
DESCRIPTION:On August 19-20\, 2019 the CMSA hosted the fifth annual Conference on Big Data. The Conference will featured many speakers from the Harvard community as well as scholars from across the globe\, with talks focusing on computer science\, statistics\, math and physics\, and economics. \nThe talks will take place in Science Center Hall D\, 1 Oxford Street. \nVideos can be found in the Youtube playlist.
URL:https://cmsa.fas.harvard.edu/event/2019-big-data-conference/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Big Data Conference,Conference,Event
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Big-Data-2019-Poster-5-2.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190429T090000
DTEND;TZID=America/New_York:20190501T170000
DTSTAMP:20260430T092023
CREATED:20230715T174721Z
LAST-MODIFIED:20250304T214254Z
UID:10000114-1556528400-1556730000@cmsa.fas.harvard.edu
SUMMARY:Conference on Algebraic Geometry\, Representation theory and Mathematical Physics
DESCRIPTION:From April 29 to May 1\, 2019 the CMSA will be hosting a Conference on Algebraic Geometry\, Representation theory and Mathematical Physics. This workshop is organized by Bong Lian (Brandeis) and Artan Sheshmani (CMSA) . The workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA.   \nVideos\nSpeakers: \n\nDan Abramovich\, Brown\nRoman Bezrukavnikov\, MIT\nFedor Bogomolov\, NYU\nQile Chen\, Boston College\nDawei Chen\, Boston College\nAlexander Efimov\, Moscow\nPavel Etingof\, MIT\nMaksym Fedorchuk\, Boston College\nDennis Gaitsgory\, Harvard\nAmin Gholampour\, Maryland\nBrendan Hassett\, Brown\nLudmil Katzarkov\, Miami & Moscow\nSi Li\, Tsinghua\nAndrei Negut\, MIT\nYuri Tschinkel\, NYU\nWei Zhang\, MIT\n\n  \nMonday\, April 29 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 10:00am\nWei Zhang\, MIT\nTitle: The arithmetic fundamental lemma for diagonal cycles \nAbstract: I’ll recall the Gross–Zagier theorem and a high dimensional generalization\, the arithmetic Gan-Gross-Prasad conjecture\, which relates the height pairing of arithmetic diagonal cycles on certain shimura varieties to the first order derivative of certain L-functions.  The arithmetic fundamental lemma conjecture arises from the relative trace formula approach to this conjecture. I will recall the statement of the arithmetic fundamental lemma and outline a proof.\n\n\n10:00 – 10:30am\nBreak\n\n\n\n10:30 – 11:30am\nYuri Tschinkel\, NYU\nTitle: Equivariant birational geometry and modular symbols \nAbstract: We introduce new invariants in equivariant birational geometry and study their relation to modular symbols and cohomology of arithmetic groups (joint with M. Kontsevich and V. Pestun).\n\n\n11:30 – 1:30pm\nLunch\n\n\n\n1:30 – 2:30pm\nAlexander Efimov\, Moscow\nTitle: Torsionness for regulators of canonical extensions \nAbstract: I will sketch a generalization of the results of Iyer and Simpson arXiv:0707.0372 to the general case of a normal-crossings divisor at infinity.\n\n\n2:30 – 3:00pm\nBreak\n\n\n\n3:00 – 4:00pm\nAmin Gholampour\, Maryland\nTitle: Euler Characteristics of punctual quot schemes on threefolds \nAbstract: Let F be a homological dimension 1 torsion free sheaf on a nonsingular quasi-projective threefold. The first cohomology of the derived dual of F is a 1-dimension sheaf G supported on the singular locus of F. We prove a wall-crossing formula relating the generating series of the Euler characteristics of Quot(F\, n) and Quot(G\,n)\, where Quot(-\,n) denotes the quot scheme of length n quotients. We will use this relation in studying the Euler characteristics of the moduli spaces of stable torsion free sheaves on nonsingular projective threefolds. This is a joint work with Martijn Kool.\n\n\n4:00 – 4:30pm\nBreak\n\n\n\n4:30 – 5:30pm\nMaksym Fedorchuck\, BC\nTitle:  Stability of one-parameter families of weighted hypersurfaces \nAbstract:  We define a notion of stability for fibrations over a curve with generic fibers being weighted hypersurfaces (in some weighted projective space) generalizing Kollár’s stability for families of hypersurfaces in a projective space.  The stability depends on a choice of an effective line bundle on the parameter space of weighted hypersurfaces and different choices pick out different birational model of the total space of the fibration. I will describe enumerative geometry that goes into understanding these stability conditions\, and\, if time permits\, examples where this machinery can be used to produce birational models with good properties.  Joint work with Hamid Ahmadinezhad and Igor Krylov.\n\n\n\n  \nTuesday\, April 30 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 10:00am\nBrendan Hassett\, Brown\nTitle: Rationality for geometrically rational threefolds \nAbstract: We consider rationality questions for varieties over non-closed fields that become rational over an algebraic closure\, like smooth complete intersections of two quadrics.  (joint with Tschinkel)\n\n\n10:00 – 10:30am\nBreak\n\n\n\n10:30 – 11:30am\nDennis Gaitsgory\, Harvard\nTitle: The Fundamental Local Equivalence in quantum geometric Langlands \nAbstract: The Fundamental Local Equivalence is statement that relates the q-twisted  Whittaker category of the affine Grassmannian for the group G and the category of modules over the Langlands dual “big” quantum group. The non-triviaiity of the statement lies is the fact that the relationship between the group and its  dual is combinatorial\, so to prove the FLE one needs to express both sides in combinatorial terms. In the talk we will indicate the proof of a related statement for the “small” quantum group. The combinatorial link is provided by the category of factorization modules over a certain factorization algebra\, which in itself is a geometric device that concisely encodes the root data.\n\n\n11:30 – 1:00pm\nLunch\n\n\n\n1:00- 2:00pm\nAndrei Negut\, MIT\nTitle: AGT relations in geometric representation theory \nAbstract: I will survey a program that seeks to translate the Alday-Gaiotto-Tachikawa correspondence (between gauge theory on R^4 and conformal field theory) into the language of algebraic geometry. The objects of study become moduli spaces of sheaves on surfaces\, and the goal is to connect them with the W-algebra of type gl_n.\n\n\n2:00 – 2:15pm\nBreak\n\n\n\n2:15 – 3:15pm\nDan Abramovich\, Brown\nTitle: Resolution in characteristic 0 using weighted blowing up \nAbstract: Given a variety $X$\, one wants to blow up the worst singular locus\, show that it gets better\, and iterate until the singularities are resolved. \nExamples such as the whitney umbrella show that this iterative process cannot be done by blowing up smooth loci – it goes into a loop. \nWe show that there is a functorial way to resolve varieties using \emph{weighted} blowings up\, in the stack-theoretic sense. To an embedded variety $X \subset Y$ one functorially assigns an invariant $(a_1\,\ldots\,a_k)$\, and a center locally of the form $(x_1^{a_1} \, \ldots \, x_k^{a_k})$\, whose stack-theoretic weighted blowing up has strictly smaller invariant under the lexicographic order. \nThis is joint work with Michael Tëmkin (Jerusalem) and Jaroslaw Wlodarczyk (Purdue)\, a side product of our work on functorial semistable reduction. A similar result was discovered by G. Marzo and M. McQuillan.\n\n\n3:15 – 3:30pm\nBreak\n\n\n\n3:30 – 4:30pm\nFedor Bogomolov\, NYU\nTitle: On the base of a Lagrangian fibration for a compact hyperkahler manifold. \nAbstract: In my talk I will discuss our proof with N. Kurnosov that the base of such fibration for complex projective manifold hyperkahler manifold of dimension $4$ is always a projective plane $P^2$. In fact we show that the base of such fibration can not have a singular point of type $E_8$. It was by the theorem of Matsushita and others that only quotient singularities can occur and if the base is smooth then the it is isomorphic to $P^2$. The absence of other singularities apart from $E_8$ has been already known and we show that $E-8$ can not occur either. Our method can be applied to other types of singularities for the study of  Lagrangian fibrations in higher dimensions More recently similar result was obtained by Huybrechts and Xu.\n\n\n4:30 – 4:45pm\nBreak\n\n\n\n4:45 – 5:45pm\nDawei Chen\, BC\nTitle: Volumes and intersection theory on moduli spaces of Abelian differentials \nAbstract: Computing volumes of moduli spaces has significance in many fields. For instance\, Witten’s conjecture regarding intersection numbers on moduli spaces of Riemann surfaces has a fascinating connection to the Weil-Petersson volume\, which motivated Mirzakhani to give a proof via Teichmueller theory\, hyperbolic geometry\, and symplectic geometry. In this talk I will introduce an analogue of Witten’s intersection numbers on moduli spaces of Abelian differentials to compute the Masur-Veech volumes induced by the flat metric associated with Abelian differentials. This is joint work with Moeller\, Sauvaget\, and Zagier (arXiv:1901.01785).\n\n\n\n  \nWednesday\, May 1 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 10:00am\nPavel Etingof\, MIT\nTitle: Short star-products for filtered quantizations \nThis is joint work with Eric Rains and Douglas Stryker.\n\n\n10:00 – 10:30am\nBreak\n\n\n\n10:30 – 11:30am\nRoman Bezrukavnikov\, MIT\nTitle: Stability conditions and representation theory \nAbstract: I will recall the concept of real variation of stabilities (introduced in my work with Anno and Mirkovic)\nand its relation to modular Lie algebra representations. I will also address a potential generalization of that picture\nto modular representations of affine Lie algebras related to the classical limit of geometric Langlands duality and its local counterpart.\n\n\n11:30 – 11:45am\nBreak\n\n\n\n11:45 – 12:45pm\nQile Chen\, BC\nTitle: Counting curves in critical locus via logarithmic compactification \nAbstract: An R-map consists of a pre-stable map to possibly non-GIT quotient together with sections of certain spin bundles. The moduli of R-maps are in general non-compact. When the target of R-maps is equipped with a super-potential W with compact critical locus\, using Kiem-Li cosection localization it has been proved by many authors in various settings that the virtual cycle of R-maps can be represented by the cosection localized virtual cycle which is supported on the proper locus consisting of R-maps in the critical locus of W. Though the moduli of R-maps is equipped with a natural torus action by scaling of the spin bundles\, the non-compactness of the R-maps moduli makes such powerful torus action useless. \nIn this talk\, I will introduce a logarithmic compactification of the moduli of R-maps using certain modifications of stable logarithmic maps. The logarithmic moduli space carries a canonical virtual cycle from the logarithmic deformation theory. In the presence of a super-potential with compact critical locus\, it further carries a reduced virtual cycle. We prove that (1) the reduced virtual cycle of the compactification can be represented by the cosection localized virtual cycle; and (2) the difference of the canonical and reduced virtual cycles is another reduced virtual cycle supported along the logarithmic boundary. As an application\, one recovers the Gromov-Witten invariants of the critical locus as the invariants of logarithmic R-maps of its ambient space in an explicit form. The latter can be calculated using the spin torus action. \nThis is a joint work with Felix Janda and Yongbin Ruan.\n\n\n12:45 – 2:30pm\nLunch\n\n\n\n2:30 – 3:30pm\nSi Li\, Tsinghua\nTitle: Semi-infinite Hodge structure: from BCOV theory to Seiberg-Witten geometry \nAbstract: I will explain how the semi-infinite Hodge theory extends Kodaira-Spencer gravity (Bershadsky-Cecotti-Ooguri-Vafa theory of B-twisted closed topological string field theory) into a full solution of Batalin-Vilkovisky master equation. This allows us to formulate quantum B-model via a rigorous BV quantization method and construct integrable hierarchies arising naturally from the background symmetry. In the second part of the talk\, I will explain the recent discovery of the connection between K.Saito’s primitive form and 4d N=2 Seiberg-Witten geometry arising from singularity theory.\n\n\n3:30 – 4:00pm\nBreak\n\n\n\n4:00 – 5:00pm\nLudmil Katzarkov\, Moscow\nTitle: PDE’s non commutative  motives and HMS. \nAbstract: In this talk we will discuss the theory of central manifolds and the new structures in geometry it produces. Application to Bir.  Geometry will be discussed.\n\n\n\n 
URL:https://cmsa.fas.harvard.edu/event/conference-on-algebraic-geometry-representation-theory-and-mathematical-physics/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Conference,Event
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/algebraic-geo-conference-final-795x1024-1-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190415T091500
DTEND;TZID=America/New_York:20190417T160000
DTSTAMP:20260430T092023
CREATED:20230715T173507Z
LAST-MODIFIED:20250304T172154Z
UID:10000112-1555319700-1555516800@cmsa.fas.harvard.edu
SUMMARY:Workshop on Invariance and Geometry in Sensation\, Action and Cognition
DESCRIPTION:As part of the program on Mathematical Biology a workshop on Invariance and Geometry in Sensation\, Action and Cognition will take place on April 15-17\, 2019. \nLegend has it that above the door to Plato’s Academy was inscribed “Μηδείς άγεωµέτρητος είσίτω µον τήν στέγην”\, translated as “Let no one ignorant of geometry enter my doors”. While geometry and invariance has always been a cornerstone of mathematics\, it has traditionally not been an important part of biology\, except in the context of aspects of structural biology. The premise of this meeting is a tantalizing sense that geometry and invariance are also likely to be important in (neuro)biology and cognition. Since all organisms interact with the physical world\, this implies that as neural systems extract information using the senses to guide action in the world\, they need appropriately invariant representations that are stable\, reproducible and capable of being learned. These invariances are a function of the nature and type of signal\, its corruption via noise\, and the method of storage and use. \nThis hypothesis suggests many puzzles and questions: What representational geometries are reflected in the brain? Are they learned or innate? What happens to the invariances under realistic assumptions about noise\, nonlinearity and finite computational resources? Can cases of mental disorders and consequences of brain damage be characterized as break downs in representational invariances? Can we harness these invariances and sensory contingencies to build more intelligent machines? The aim is to revisit these old neuro-cognitive problems using a series of modern lenses experimentally\, theoretically and computationally\, with some tutorials on how the mathematics and engineering of invariant representations in machines and algorithms might serve as useful null models. \nIn addition to talks\, there will be a set of tutorial talks on the mathematical description of invariance (P.J. Olver)\, the computer vision aspects of invariant algorithms (S. Soatto)\, and the neuroscientific and cognitive aspects of invariance (TBA). The workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. This workshop is organized by L. Mahadevan (Harvard)\, Talia Konkle (Harvard)\, Samuel Gershman (Harvard)\, and Vivek Jayaraman (HHMI). \nVideos\nTentative Speaker List: \n\nAlessandro Achille\, UCLA\nVijay Balasubramanian\, University of Pennsylvania\nJeannette Bohg\, Stanford\nEd Connor\, Johns Hopkins\nMoira Dillon\, NYU\nJacob Feldman\, Rutgers\nIla Fiete\, MIT\nSam Gershman\, Harvard\nGily Ginosar\, Weizmann Institute of Science\nLucia Jacobs\, UC Berkeley\nVivek Jayaraman\, HHMI\nTalia Konkle\, Harvard\nL. Mahadevan\, Harvard\nMichael McCloskey\, Johns Hopkins\nSam Ocko\, Stanford\nPeter Olver\, University of Minnesota\nAnitha Pasupathy\, University of Washington\nSandro Romani\, Janelia\nStefano Soatto\, UCLA\nTatyana Sharpee\,  Salk Institute\nDagmar Sternad\, Northeastern\nElizabeth Torres\, Rutgers\n\nSchedule:\nMonday\, April 15 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 9:15am\nWelcome and Introduction\n\n\n\n9:15 – 10:00am\nVivek Jayaraman\nTitle: Insect cognition: Small tales of geometry & invariance \nAbstract: Decades of field and laboratory experiments have allowed ethologists to discover the remarkable sophistication of insect behavior. Over the past couple of decades\, physiologists have been able to peek under the hood to uncover sophistication in insect brain dynamics as well. In my talk\, I will describe phenomena that relate to the workshop’s theme of geometry and invariance. I will outline how studying insects —and flies in particular— may enable an understanding of the neural mechanisms underlying these intriguing phenomena.\n\n\n10:00 – 10:45am\nElizabeth Torres\nTitle: Connecting Cognition and Biophysical Motions Through Geometric Invariants and Motion Variability \nAbstract: In the 1930s Nikolai Bernstein defined the degrees of freedom (DoF) problem. He asked how the brain could control abundant DoF and produce consistent solutions\, when the internal space of bodily configurations had much higher dimensions than the space defining the purpose(s) of our actions. His question opened two fundamental problems in the field of motor control. One relates to the uniqueness or consistency of a solution to the DoF problem\, while the other refers to the characterization of the diverse patterns of variability that such solution produces. \nIn this talk I present a general geometric solution to Bernstein’s DoF problem and provide empirical evidence for symmetries and invariances that this solution provides during the coordination of complex naturalistic actions. I further introduce fundamentally different patterns of variability that emerge in deliberate vs. spontaneous movements discovered in my lab while studying athletes and dancers performing interactive actions. I here reformulate the DoF problem from the standpoint of the social brain and recast it considering graph theory and network connectivity analyses amenable to study one of the most poignant developmental disorders of our times: Autism Spectrum Disorders. \nI offer a new unifying framework to recast dynamic and complex cognitive and social behaviors of the full organism and to characterize biophysical motion patterns during migration of induced pluripotent stem cell colonies on their way to become neurons.\n\n\n10:45 – 11:15am\nCoffee Break\n\n\n\n11:15 – 12:00pm\nPeter Olver\nTitle: Symmetry and invariance in cognition — a mathematical perspective” \nAbstract: Symmetry recognition and appreciation is fundamental in human cognition.  (It is worth speculating as to why this may be so\, but that is not my intent.) The goal of these two talks is to survey old and new mathematical perspectives on symmetry and invariance.  Applications will arise from art\, computer vision\, geometry\, and beyond\, and will include recent work on 2D and 3D jigsaw puzzle assembly and an ongoing collaboration with anthropologists on the analysis and refitting of broken bones.  Mathematical prerequisites will be kept to a bare minimum.\n\n\n12:00 – 12:45pm\nStefano Soatto/Alessandro Achille\nTitle: Information in the Weights and Emergent Properties of Deep Neural Networks \nAbstract: We introduce the notion of information contained in the weights of a Deep Neural Network  and show that it can be used to control and describe the training process of DNNs\, and can explain how properties\, such as invariance to nuisance variability and disentanglement\, emerge naturally in the learned representation. Through its dynamics\, stochastic gradient descent (SGD) implicitly regularizes the information in the weights\, which can then be used to bound the generalization error through the PAC-Bayes bound. Moreover\, the information in the weights can be used to defined both a topology and an asymmetric distance in the space of tasks\, which can then be used to predict the training time and the performance on a new task given a solution to a pre-training task. \nWhile this information distance models difficulty of transfer in first approximation\, we show the existence of non-trivial irreversible dynamics during the initial transient phase of convergence when the network is acquiring information\, which makes the approximation fail. This is closely related to critical learning periods in biology\, and suggests that studying the initial convergence transient can yield important insight beyond those that can be gleaned from the well-studied asymptotics.\n\n\n12:45 – 2:00pm\nLunch\n\n\n\n2:00 – 2:45pm\nAnitha Pasupathy\nTitle: Invariant and non-invariant representations in mid-level ventral visual cortex \nMy laboratory investigates how visual form is encoded in area V4\, a critical mid-level stage of form processing in the macaque monkey. Our goal is to reveal how V4 representations underlie our ability to segment visual scenes and recognize objects. In my talk I will present results from two experiments that highlight the different strategies used by the visual to achieve these goals. First\, most V4 neurons exhibit form tuning that is exquisitely invariant to size and position\, properties likely important to support invariant object recognition. On the other hand\, form tuning in a majority of neurons is also highly dependent on the interior fill. Interestingly\, unlike primate V4 neurons\, units in a convolutional neural network trained to recognize objects (AlexNet) overwhelmingly exhibit fill-outline invariance. I will argue that this divergence between real and artificial circuits reflects the importance of local contrast in parsing visual scenes and overall scene understanding.\n\n\n2:45 – 3:30pm\nJacob Feldman\nTitle: Bayesian skeleton estimation for shape representation and perceptual organization \nAbstract: In this talk I will briefly summarize a framework in which shape representation and perceptual organization are reframed as probabilistic estimation problems. The approach centers around the goal of identifying the skeletal model that best “explains” a given shape. A Bayesian solution to this problem requires identifying a prior over shape skeletons\, which penalizes complexity\, and a likelihood model\, which quantifies how well any particular skeleton model fits the data observed in the image. The maximum-posterior skeletal model thus constitutes the most “rational” interpretation of the image data consistent with the given assumptions. This approach can easily be extended and generalized in a number of ways\, allowing a number of traditional problems in perceptual organization to be “probabilized.” I will briefly illustrate several such extensions\, including (1) figure/ground and grouping (3) 3D shape and (2) shape similarity.\n\n\n3:30 – 4:00pm\nTea Break\n\n\n\n4:00 – 4:45pm\nMoira Dillon\nTitle: Euclid’s Random Walk: Simulation as a tool for geometric reasoning through development \nAbstract: Formal geometry lies at the foundation of millennia of human achievement in domains such as mathematics\, science\, and art. While formal geometry’s propositions rely on abstract entities like dimensionless points and infinitely long lines\, the points and lines of our everyday world all have dimension and are finite. How\, then\, do we get to abstract geometric thought? In this talk\, I will provide evidence that evolutionarily ancient and developmentally precocious sensitivities to the geometry of our everyday world form the foundation of\, but also limit\, our mathematical reasoning. I will also suggest that successful geometric reasoning may emerge through development when children abandon incorrect\, axiomatic-based strategies and come to rely on dynamic simulations of physical entities. While problems in geometry may seem answerable by immediate inference or by deductive proof\, human geometric reasoning may instead rely on noisy\, dynamic simulations.\n\n\n4:45 – 5:30pm\nMichael McCloskey\nTitle: Axes and Coordinate Systems in Representing Object Shape and Orientation \nAbstract: I describe a theoretical perspective in which a) object shape is represented in an object-centered reference frame constructed around orthogonal axes; and b) object orientation is represented by mapping the object-centered frame onto an extrinsic (egocentric or environment-centered) frame.  I first show that this perspective is motivated by\, and sheds light on\, object orientation errors observed in neurotypical children and adults\, and in a remarkable case of impaired orientation perception. I then suggest that orientation errors can be used to address questions concerning how object axes are defined on the basis of object geometry—for example\, what aspects of object geometry (e.g.\, elongation\, symmetry\, structural centrality of parts) play a role in defining an object principal axis?\n\n\n5:30 – 6:30pm\nReception\n\n\n\n\n \nTuesday\, April 16 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 9:45am\nPeter Olver\nTitle: Symmetry and invariance in cognition — a mathematical perspective” \nAbstract: Symmetry recognition and appreciation is fundamental in human cognition.  (It is worth speculating as to why this may be so\, but that is not my intent.) The goal of these two talks is to survey old and new mathematical perspectives on symmetry and invariance.  Applications will arise from art\, computer vision\, geometry\, and beyond\, and will include recent work on 2D and 3D jigsaw puzzle assembly and an ongoing collaboration with anthropologists on the analysis and refitting of broken bones.  Mathematical pre\n\n\n9:45 – 10:30am\nStefano Soatto/Alessandro Achille\nTitle: Information in the Weights and Emergent Properties of Deep Neural Networks \nAbstract: We introduce the notion of information contained in the weights of a Deep Neural Network  and show that it can be used to control and describe the training process of DNNs\, and can explain how properties\, such as invariance to nuisance variability and disentanglement\, emerge naturally in the learned representation. Through its dynamics\, stochastic gradient descent (SGD) implicitly regularizes the information in the weights\, which can then be used to bound the generalization error through the PAC-Bayes bound. Moreover\, the information in the weights can be used to defined both a topology and an asymmetric distance in the space of tasks\, which can then be used to predict the training time and the performance on a new task given a solution to a pre-training task. \nWhile this information distance models difficulty of transfer in first approximation\, we show the existence of non-trivial irreversible dynamics during the initial transient phase of convergence when the network is acquiring information\, which makes the approximation fail. This is closely related to critical learning periods in biology\, and suggests that studying the initial convergence transient can yield important insight beyond those that can be gleaned from the well-studied asymptotics.\n\n\n10:30 – 11:00am\nCoffee Break\n\n\n\n11:00 – 11:45am\nJeannette Bohg\nTitle: On perceptual representations and how they interact with actions and physical representations \nAbstract: I will discuss the hypothesis that perception is active and shaped by our task and our expectations on how the world behaves upon physical interaction. Recent approaches in robotics follow this insight that perception is facilitated by physical interaction with the environment. First\, interaction creates a rich sensory signal that would otherwise not be present. And second\, knowledge of the regularity in the combined space of sensory data and action parameters facilitate the prediction and interpretation of the signal. In this talk\, I will present two examples from our previous work where a predictive task facilitates autonomous robot manipulation by biasing the representation of the raw sensory data. I will present results on visual but also haptic data.\n\n\n11:45 – 12:30pm\nDagmar Sternad\nTitle: Exploiting the Geometry of the Solution Space to Reduce Sensitivity to Neuromotor Noise \nAbstract: Control and coordination of skilled action is frequently examined in isolation as a neuromuscular problem. However\, goal-directed actions are guided by information that creates solutions that are defined as a relation between the actor and the environment. We have developed a task-dynamic approach that starts with a physical model of the task and mathematical analysis of the solution spaces for the task. Based on this analysis we can trace how humans develop strategies that meet complex demands by exploiting the geometry of the solution space. Using three interactive tasks – throwing or bouncing a ball and transporting a “cup of coffee” – we show that humans develop skill by: 1) finding noise-tolerant strategies and channeling noise into task-irrelevant dimensions\, 2) exploiting solutions with dynamic stability\, and 3) optimizing predictability of the object dynamics. These findings are the basis for developing propositions about the controller: complex actions are generated with dynamic primitives\, attractors with few invariant types that overcome substantial delays and noise in the neuro-mechanical system.\n\n\n12:30 – 2:00pm\nLunch\n\n\n\n2:00 – 2:45pm\nSam Ocko\nTitle: Emergent Elasticity in the Neural Code for Space \nAbstract: To navigate a novel environment\, animals must construct an internal map of space by combining information from two distinct sources: self-motion cues and sensory perception of landmarks. How do known aspects of neural circuit dynamics and synaptic plasticity conspire to construct such internal maps\, and how are these maps used to maintain representations of an animal’s position within an environment. We demonstrate analytically how a neural attractor model that combines path integration of self-motion with Hebbian plasticity in synaptic weights from landmark cells can self-organize a consistent internal map of space as the animal explores an environment. Intriguingly\, the emergence of this map can be understood as an elastic relaxation process between landmark cells mediated by the attractor network during exploration. Moreover\, we verify several experimentally testable predictions of our model\, including: (1) systematic deformations of grid cells in irregular environments\, (2) path-dependent shifts in grid cells towards the most recently encountered landmark\, (3) a dynamical phase transition in which grid cells can break free of landmarks in altered virtual reality environments and (4) the creation of topological defects in grid cells. Taken together\, our results conceptually link known biophysical aspects of neurons and synapses to an emergent solution of a fundamental computational problem in navigation\, while providing a unified account of disparate experimental observations.\n\n\n2:45 – 3:30pm\nTatyana Sharpee\nTitle: Hyperbolic geometry of the olfactory space \nAbstract: The sense of smell can be used to avoid poisons or estimate a food’s nutrition content because biochemical reactions create many by-products. Thus\, the production of a specific poison by a plant or bacteria will be accompanied by the emission of certain sets of volatile compounds. An animal can therefore judge the presence of poisons in the food by how the food smells. This perspective suggests that the nervous system can classify odors based on statistics of their co-occurrence within natural mixtures rather than from the chemical structures of the ligands themselves. We show that this statistical perspective makes it possible to map odors to points in a hyperbolic space. Hyperbolic coordinates have a long but often underappreciated history of relevance to biology. For example\, these coordinates approximate distance between species computed along dendrograms\, and more generally between points within hierarchical tree-like networks. We find that both natural odors and human perceptual descriptions of smells can be described using a three-dimensional hyperbolic space. This match in geometries can avoid distortions that would otherwise arise when mapping odors to perception. We identify three axes in the perceptual space that are aligned with odor pleasantness\, its molecular boiling point and acidity. Because the perceptual space is curved\, one can predict odor pleasantness by knowing the coordinates along the molecular boiling point and acidity axes.\n\n\n3:30 – 4:00pm\nTea Break\n\n\n\n4:00 – 4:45pm\nEd Connor\nTitle: Representation of solid geometry in object vision cortex \nAbstract: There is a fundamental tension in object vision between the 2D nature of retinal images and the 3D nature of physical reality. Studies of object processing in the ventral pathway of primate visual cortex have focused mainly on 2D image information. Our latest results\, however\, show that representations of 3D geometry predominate even in V4\, the first object-specific stage in the ventral pathway. The majority of V4 neurons exhibit strong responses and clear selectivity for solid\, 3D shape fragments. These responses are remarkably invariant across radically different image cues for 3D shape: shading\, specularity\, reflection\, refraction\, and binocular disparity (stereopsis). In V4 and in subsequent stages of the ventral pathway\, solid shape geometry is represented in terms of surface fragments and medial axis fragments. Whole objects are represented by ensembles of neurons signaling the shapes and relative positions of their constituent parts. The neural tuning dimensionality of these representations includes principal surface curvatures and their orientations\, surface normal orientation\, medial axis orientation\, axial curvature\, axial topology\, and position relative to object center of mass. Thus\, the ventral pathway implements a rapid transformation of 2D image data into explicit representations 3D geometry\, providing cognitive access to the detailed structure of physical reality.\n\n\n4:45 – 5:30pm\nL. Mahadevan\nTitle: Simple aspects of geometry and probability in perception \nAbstract: Inspired by problems associated with noisy perception\, I will discuss two questions: (i) how might we test people’s perception of probability in a geometric context ? (ii) can one construct invariant descriptions of 2D images using simple notions of probabilistic geometry? Along the way\, I will highlight other questions that the intertwining of geometry and probability raises in a broader perceptual context.\n\n\n\n\nWednesday\, April 17 \n\n\n\nTime\nSpeaker\nTitle/Abstract\n\n\n8:30 – 9:00am\nBreakfast\n\n\n\n9:00 – 9:45am\nGily Ginosar\nTitle: The 3D geometry of grid cells in flying bats \nAbstract: The medial entorhinal cortex (MEC) contains a variety of spatial cells\, including grid cells and border cells. In 2D\, grid cells fire when the animal passes near the vertices of a 2D spatial lattice (or grid)\, which is characterized by circular firing-fields separated by fixed distances\, and 60 local angles – resulting in a hexagonal structure. Although many animals navigate in 3D space\, no studies have examined the 3D volumetric firing of MEC neurons. Here we addressed this by training Egyptian fruit bats to fly in a large room (5.84.62.7m)\, while we wirelessly recorded single neurons in MEC. We found 3D border cells and 3D head-direction cells\, as well as many neurons with multiple spherical firing-fields. 20% of the multi-field neurons were 3D grid cells\, exhibiting a narrow distribution of characteristic distances between neighboring fields – but not a perfect 3D global lattice. The 3D grid cells formed a functional continuum with less structured multi-field neurons. Both 3D grid cells and multi-field cells exhibited an anatomical gradient of spatial scale along the dorso-ventral axis of MEC\, with inter-field spacing increasing ventrally – similar to 2D grid cells in rodents. We modeled 3D grid cells and multi-field cells as emerging from pairwise-interactions between fields\, using an energy potential that induces repulsion at short distances and attraction at long distances. Our analysis shows that the model explains the data significantly better than a random arrangement of fields. Interestingly\, simulating the exact same model in 2D yielded a hexagonal-like structure\, akin to grid cells in rodents. Together\, the experimental data and preliminary modeling suggest that the global property of grid cells is multiple fields that repel each other with a characteristic distance-scale between adjacent fields – which in 2D yields a global hexagonal lattice while in 3D yields only local structure but no global lattice. \nGily Ginosar 1 \, Johnatan Aljadeff 2 \, Yoram Burak 3 \, Haim Sompolinsky 3 \, Liora Las 1 \, Nachum Ulanovsky 1 \n(1) Department of Neurobiology\, Weizmann Institute of Science\, Rehovot 76100\, Israel \n(2) Department of Bioengineering\, Imperial College London\, London\, SW7 2AZ\, UK \n(3) The Edmond and Lily Safra Center for Brain Sciences\, and Racah Institute of Physics\, The Hebrew \nUniversity of Jerusalem\, Jerusalem\, 91904\, Israel\n\n\n9:45 – 10:30am\nSandro Romani\nTitle: Neural networks for 3D rotations \nAbstract: Studies in rodents\, bats\, and humans have uncovered the existence of neurons that encode the orientation of the head in 3D. Classical theories of the head-direction (HD) system in 2D rely on continuous attractor neural networks\, where neurons with similar heading preference excite each other\, while inhibiting other HD neurons. Local excitation and long-range inhibition promote the formation of a stable “bump” of activity that maintains a representation of heading. The extension of HD models to 3D is hindered by complications (i) 3D rotations are non-commutative (ii) the space described by all possible rotations of an object has a non-trivial topology. This topology is not captured by standard parametrizations such as Euler angles (e.g. yaw\, pitch\, roll). For instance\, with these parametrizations\, a small change of the orientation of the head could result in a dramatic change of neural representation. We used methods from the representation theory of groups to develop neural network models that exhibit patterns of persistent activity of neurons mapped continuously to the group of 3D rotations. I will further discuss how these networks can (i) integrate vestibular inputs to update the representation of heading\, and (ii) be used to interpret “mental rotation” experiments in humans. \nThis is joint work with Hervé Rouault (CENTURI) and Alon Rubin (Weizmann Institute of Science).\n\n\n10:30 – 11:00am\nCoffee Break\n\n\n\n11:00 – 11:45am\nSam Gershman\nTitle: The hippocampus as a predictive map \nAbstract: A cognitive map has long been the dominant metaphor for hippocampal function\, embracing the idea that place cells encode a geometric representation of space. However\, evidence for predictive coding\, reward sensitivity and policy dependence in place cells suggests that the representation is not purely spatial. I approach this puzzle from a reinforcement learning perspective: what kind of spatial representation is most useful for maximizing future reward? I show that the answer takes the form of a predictive representation. This representation captures many aspects of place cell responses that fall outside the traditional view of a cognitive map. Furthermore\, I argue that entorhinal grid cells encode a low-dimensionality basis set for the predictive representation\, useful for suppressing noise in predictions and extracting multiscale structure for hierarchical planning.\n\n\n11:45 – 12:30pm\nLucia Jacobs\nTitle: The adaptive geometry of a chemosensor: the origin and function of the vertebrate nose \nAbstract: A defining feature of a living organism\, from prokaryotes to plants and animals\, is the ability to orient to chemicals. The distribution of chemicals\, whether in water\, air or on land\, is used by organisms to locate and exploit spatially distributed resources\, such as nutrients and reproductive partners. In animals\, the evolution of a nervous system coincided with the evolution of paired chemosensors. In contemporary insects\, crustaceans\, mollusks and vertebrates\, including humans\, paired chemosensors confer a stereo olfaction advantage on the animal’s ability to orient in space. Among vertebrates\, however\, this function faced a new challenge with the invasion of land. Locomotion on land created a new conflict between respiration and spatial olfaction in vertebrates. The need to resolve this conflict could explain the current diversity of vertebrate nose geometries\, which could have arisen due to species differences in the demand for stereo olfaction. I will examine this idea in more detail in the order Primates\, focusing on Old World primates\, in particular\, the evolution of an external nose in the genus Homo.\n\n\n12:30 – 1:30pm\nLunch\n\n\n\n1:30 – 2:15pm\nTalia Konkle\nTitle: The shape of things and the organization of object-selective cortex \nAbstract: When we look at the world\, we effortlessly recognize the objects around us and can bring to mind a wealth of knowledge about their properties. In part 1\, I’ll present evidence that neural responses to objects are organized by high-level dimensions of animacy and size\, but with underlying neural tuning to mid-level shape features. In part 2\, I’ll present evidence that representational structure across much of the visual system has the requisite structure to predict visual behavior. Together\, these projects suggest that there is a ubiquitous “shape space” mapped across all of occipitotemporal cortex that underlies our visual object processing capacities. Based on these findings\, I’ll speculate that the large-scale spatial topography of these neural responses is critical for pulling explicit content out of a representational geometry.\n\n\n2:15 – 3:00pm\nVijay Balasubramanian\nTitle: Becoming what you smell: adaptive sensing in the olfactory system \nAbstract: I will argue that the circuit architecture of the early olfactory system provides an adaptive\, efficient mechanism for compressing the vast space of odor mixtures into the responses of a small number of sensors.  In this view\, the olfactory sensory repertoire employs a disordered code to compress a high dimensional olfactory space into a low dimensional receptor response space while preserving distance relations between odors.  The resulting representation is dynamically adapted to efficiently encode the changing environment of volatile molecules.  I will show that this adaptive combinatorial code can be efficiently decoded by systematically eliminating candidate odorants that bind to silent receptors.  The resulting algorithm for “estimation by elimination” can be implemented by a neural network that is remarkably similar to the early olfactory pathway in the brain.  The theory predicts a relation between the diversity of olfactory receptors and the sparsity of their responses that matches animals from flies to humans.   It also predicts specific deficits in olfactory behavior that should result from optogenetic manipulation of the olfactory bulb.\n\n\n3:00 – 3:45pm\nIla Feite\nTitle: Invariance\, stability\, geometry\, and flexibility in spatial navigation circuits \nAbstract: I will describe how the geometric invariances or symmetries of the external world are reflected in the symmetries of neural circuits that represent it\, using the example of the brain’s networks for spatial navigation. I will discuss how these symmetries enable spatial memory\, evidence integration\, and robust representation. At the same time\, I will discuss how these seemingly rigid circuits with their inscribed symmetries can be harnessed to represent a range of spatial and non-spatial cognitive variables with high flexibility.\n\n\n3:45 – 4:00pm\nL Mahadevan – summary
URL:https://cmsa.fas.harvard.edu/event/workshop-on-invariance-and-geometry-in-sensation-action-and-cognition/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190410T143000
DTEND;TZID=America/New_York:20190410T153000
DTSTAMP:20260430T092023
CREATED:20240212T112326Z
LAST-MODIFIED:20240514T181503Z
UID:10002069-1554906600-1554910200@cmsa.fas.harvard.edu
SUMMARY:Inequality Aversion\, Populism\, and the Backlash Against Globalization
DESCRIPTION:Speaker: Pietro Veronesi (University of Chicago) \nTitle: Inequality Aversion\, Populism\, and the Backlash Against Globalization \nAbstract: Motivated by the recent rise of populism in western democracies\, we develop a model in which a populist backlash emerges endogenously in a growing economy. In the model\, voters dislike inequality\, especially the high consumption of “elites.” Economic growth exacerbates inequality due to heterogeneity in risk aversion. In response to rising inequality\, rich-country voters optimally elect a populist promising to end globalization. Countries with more inequality\, higher financial development\, and current account deficits are more vulnerable to populism\, both in the model and in the data. Evidence on who voted for Brexit and Trump in 2016 also supports the model.
URL:https://cmsa.fas.harvard.edu/event/4-10-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-041019-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190403T143000
DTEND;TZID=America/New_York:20190403T153000
DTSTAMP:20260430T092023
CREATED:20240212T112705Z
LAST-MODIFIED:20240514T181644Z
UID:10002077-1554301800-1554305400@cmsa.fas.harvard.edu
SUMMARY:Deregulation through Direct Democracy: Lessons from Liquor
DESCRIPTION:Speaker:  Sarah Moshary (University of Chicago) \nTitle:  Deregulation through Direct Democracy: Lessons from Liquor \nAbstract:  This paper examines the merits of state control versus private provision of spirits retail\, using the 2012 deregulation of liquor sales in Washington state as an event study. We document effects along a number of dimensions: prices\, product variety\, convenience\, substitution to other goods\, state revenue\, and consumption externalities. We estimate a demand system to evaluate the net effect of privatization on consumer welfare. Our findings suggest that deregulation harmed the median Washingtonian\, even though residents voted in favor of deregulation by a 16% margin. Further\, we find that vote shares for the deregulation initiative do not reflect welfare gains at the ZIP code level. We discuss implications of our findings for the efficacy of direct democracy as a policy tool.
URL:https://cmsa.fas.harvard.edu/event/4-3-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-040319.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190327T171500
DTEND;TZID=America/New_York:20190327T181500
DTSTAMP:20260430T092023
CREATED:20240212T110407Z
LAST-MODIFIED:20240514T181829Z
UID:10002031-1553706900-1553710500@cmsa.fas.harvard.edu
SUMMARY:Hyperbolic geometry of the olfactory space
DESCRIPTION:Speaker: Tatyana Sharpee (Salk Institute for Biological Studies) \nTitle: Hyperbolic geometry of the olfactory space \nAbstract: The sense of smell can be used to avoid poisons or estimate a food’s nutrition content because biochemical reactions create many by-products. Thus\, the presence of certain bacteria in the food becomes associated with the emission of certain volatile compounds. This perspective suggests that it would be convenient for the nervous system encode odors based on statistics of their co-occurrence within natural mixtures rather than based on the chemical structure per se. I will discuss how this statistical perspective makes it possible to map odors to points in a hyperbolic space. Hyperbolic coordinates have a long but often underappreciated history of relevance to biology. For example\, these coordinates approximate distance between species computed along dendograms\, and more generally between points within hierarchical tree-like networks. We find that these coordinates\, which were generated purely based on the statistics of odors in the natural environment\, provide a contiguous map of human odor pleasantness. Further\, a separate analysis of human perceptual descriptions of smells indicates that these also generate a three dimensional hyperbolic representation of odors. This match in geometries between natural odor statistics and human perception can help to minimize distortions that would otherwise arise when mapping odors to perception. We identify three axes in the perceptual space that are aligned with odor pleasantness\, its molecular boiling point and acidity. Because the perceptual space is curved\, one can predict odor pleasantness by knowing the coordinates along the molecular boiling point and acidity axes. \n  \n 
URL:https://cmsa.fas.harvard.edu/event/3-27-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-032719.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190320T163000
DTEND;TZID=America/New_York:20190320T173000
DTSTAMP:20260430T092023
CREATED:20240212T105115Z
LAST-MODIFIED:20240507T204308Z
UID:10002015-1553099400-1553103000@cmsa.fas.harvard.edu
SUMMARY:Quality Externalities on Platforms: The Case of Airbnb
DESCRIPTION:Speaker:  Sonia Jaffe  (Microsoft) \nTitle: Quality Externalities on Platforms: The Case of Airbnb \nAbstract:  We explore quality externalities on platforms: when buyers have limited information\, a seller’s quality affects whether her buyers return to the platform\, thereby impacting other sellers’ future business. We propose an intuitive measure of this externality\, applicable across a range of platforms. Guest Return Propensity (GRP) is the aggregate propensity of a seller’s customers to return to the platform. We validate this metric using Airbnb data: matching customers to listings with a one standard deviation higher GRP causes them to take 17% more subsequent trips. By directing buyers to higher-GRP sellers\, platforms may be able to increase overall seller surplus. (Joint work with Peter Coles\, Steven Levitt\, and Igor Popov.)
URL:https://cmsa.fas.harvard.edu/event/3-20-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=application/pdf:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-032019.pdf
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190318T090000
DTEND;TZID=America/New_York:20190320T170000
DTSTAMP:20260430T092023
CREATED:20230715T091111Z
LAST-MODIFIED:20250304T213630Z
UID:10000109-1552899600-1553101200@cmsa.fas.harvard.edu
SUMMARY:Workshop on Mirror Symmetry and Stability
DESCRIPTION:This three-day workshop will take place at Harvard University on March 18-20\, 2019 in Science Center room 507. The main topic will be stability conditions in homological mirror symmetry. This workshop is funded by the Simons Collaboration in Homological Mirror Symmetry. \nOrganizers: Denis Auroux\, Yu-Wei Fan\, Hansol Hong\, Siu-Cheong Lau\, Bong Lian\, Shing-Tung Yau\, Jingyu Zhao \nSpeakers: \nDylan Allegretti (Sheffield)\nTristan Collins (MIT)\nNaoki Koseki (Tokyo)\nChunyi Li (Warwick)\nJason Lo (CSU Northridge)\nEmanuele Macrì (NEU & IHES)\nGenki Ouchi (Riken iTHEMS)\nPranav Pandit (ICTS)\nLaura Pertusi (Edinburgh)\nJacopo Stoppa (SISSA)\nAlex Takeda (UC Berkeley)\nXiaolei Zhao (UC Santa Barbara) \nMore details will be added later. \nVisit the event page for more information.  \n  \n 
URL:https://cmsa.fas.harvard.edu/event/workshop-on-mirror-symmetry-and-stability/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/HMS-2019-1-768x994-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190313T171500
DTEND;TZID=America/New_York:20190313T181500
DTSTAMP:20260430T092023
CREATED:20240212T105402Z
LAST-MODIFIED:20240514T182140Z
UID:10002017-1552497300-1552500900@cmsa.fas.harvard.edu
SUMMARY:On the geometry and topology of initial data sets in General Relativity
DESCRIPTION:Speaker: Greg Galloway (University of Miami) \nTitle: On the geometry and topology of initial data sets in General Relativity \nAbstract: A theme of long standing interest (to the speaker!) concerns the relationship between the topology of spacetime and the occurrence of singularities (causal geodesic incompleteness). Many results concerning this center around the notion of topological censorship\, which has to do with the idea that the region outside all black holes (and white holes) should be simple. The aim of the results to be presented is to provide support for topological censorship at the pure initial data level\, thereby circumventing difficult issues of global evolution. The proofs rely on the recently developed theory of marginally outer trapped surfaces\, which are natural spacetime analogues of minimal surfaces in Riemannian geometry. The talk will begin with a brief overview of general relativity and topological censorship. The talk is based primarily on joint work with various collaborators: Lars Andersson\, Mattias Dahl\, Michael Eichmair and Dan Pollack.
URL:https://cmsa.fas.harvard.edu/event/2-13-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-031319-791x1024-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190313T090000
DTEND;TZID=America/New_York:20190315T170000
DTSTAMP:20260430T092023
CREATED:20230717T174351Z
LAST-MODIFIED:20250305T192752Z
UID:10000046-1552467600-1552669200@cmsa.fas.harvard.edu
SUMMARY:Fluid turbulence and Singularities of the Euler/ Navier Stokes equations
DESCRIPTION:The Workshop on Fluid turbulence and Singularities of the Euler/ Navier Stokes equations will take place on March 13-15\, 2019. This is the first of two workshop organized by Michael Brenner\, Shmuel Rubinstein\, and Tom Hou. The second\, Machine Learning for Multiscale Model Reduction\, will take place on March 27-29\, 2019. Both workshops will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA. \n  \nSpeakers: \n\nClaude Bardos\, University of Paris\nJiajie Chen\, Caltech\nPeter Constantin\, Princeton\nDiego Cordoba\, ICMAT\nTarek Elgindi\, UCSD\nSusumu Goto\, Osaka\nAlexander Kiselev\, Duke University\nAlain Pumir\, ENS Lyon\nShmuel Rubinstein\, Harvard SEAS\nVladimir Sverak\, University of Minnesota\nEdriss S. Titi\, TAMU\nVlad Vicol\, Courant\nSijue Wu\, University of Michigan\nAndrej Zlatos\, UCSD
URL:https://cmsa.fas.harvard.edu/event/fluid-turbulence-and-singularities-of-the-euler-navier-stokes-equations/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Fluid-Turbulence-Poster-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190228T143000
DTEND;TZID=America/New_York:20190228T150000
DTSTAMP:20260430T092023
CREATED:20240212T104226Z
LAST-MODIFIED:20240514T182343Z
UID:10002002-1551364200-1551366000@cmsa.fas.harvard.edu
SUMMARY:A sharp transition for Gibbs measures associated to the nonlinear Schrödinger equation
DESCRIPTION:Speaker: Philippe Sosoe (Cornell) \nTitle: A sharp transition for Gibbs measures associated to the nonlinear Schrödinger equation \nAbstract: In 1987\, Lebowitz\, Rose and Speer (LRS) showed how to construct formally invariant measures for the nonlinear Schrödinger equation on the torus. This seminal contribution spurred a large amount of activity in the area of partial differential equations with random initial data. In this talk\, I will explain LRS’s result\, and discuss a sharp transition in the construction of the Gibbs-type invariant measures considered by these authors. (Joint work with Tadahiro Oh and Leonardo Tolomeo)
URL:https://cmsa.fas.harvard.edu/event/3-6-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-030619-791x1024-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190227T143000
DTEND;TZID=America/New_York:20190227T153000
DTSTAMP:20260430T092023
CREATED:20240212T102330Z
LAST-MODIFIED:20240514T182606Z
UID:10001978-1551277800-1551281400@cmsa.fas.harvard.edu
SUMMARY:Sentiment and Speculation in a Market with Heterogeneous Beliefs
DESCRIPTION:Speaker: Ian Martin (LSE) \nTitle: Sentiment and Speculation in a Market with Heterogeneous Beliefs \nAbstract: We present a dynamic model featuring risk-averse investors with heterogeneous beliefs. Individual investors have stable beliefs and risk aversion\, but agents who were correct in hindsight become relatively wealthy; their beliefs are overrepresented in market sentiment\, so “the market” is bullish following good news and bearish following bad news. Extreme states are far more important than in a homogeneous economy. Investors understand that sentiment drives volatility up\, and demand high risk premia in compensation. Moderate investors supply liquidity: they trade against market sentiment in the hope of capturing a variance risk premium created by the presence of extremists. [Joint work with Dimitris Papadimitriou] \n  \n 
URL:https://cmsa.fas.harvard.edu/event/2-27-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-022719-e1550767365109.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190225T093000
DTEND;TZID=America/New_York:20190301T170000
DTSTAMP:20260430T092023
CREATED:20230715T090551Z
LAST-MODIFIED:20240209T214453Z
UID:10000108-1551087000-1551459600@cmsa.fas.harvard.edu
SUMMARY:Growth and zero sets of eigenfunctions and of solutions to elliptic partial differential equations
DESCRIPTION:From February 25 to March 1\, the CMSA will be hosting a workshop on Growth and zero sets of eigenfunctions and of solutions to elliptic partial differential equations.  \nKey participants of this workshop include David Jerison (MIT)\, Alexander Logunov (IAS)\, and Eugenia Malinnikova (IAS).  This workshop will have morning sessions on Monday-Friday of this week from 9:30-11:30am\, and afternoon sessions on Monday\, Tuesday\, and Thursday from 3:00-5:00pm.\nThe sessions will be held in  \(G02\) (downstairs) at 20 Garden\, except for Tuesday afternoon\, when the talk will be in \(G10\).
URL:https://cmsa.fas.harvard.edu/event/growth-and-zero-sets-of-eigenfunctions-and-of-solutions-to-elliptic-partial-differential-equations/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190220T163000
DTEND;TZID=America/New_York:20190220T173000
DTSTAMP:20260430T092023
CREATED:20240212T114533Z
LAST-MODIFIED:20240514T182813Z
UID:10002102-1550680200-1550683800@cmsa.fas.harvard.edu
SUMMARY:Optimally Imprecise Memory and Biased Forecasts
DESCRIPTION:Speaker: Michael Woodford (Columbia) \nTitle: Optimally Imprecise Memory and Biased Forecasts \nAbstract: We propose a model of optimal decision making subject to a memory constraint. The constraint is a limit on the complexity of memory measured using Shannon’s mutual information\, as in models of rational inattention; the structure of the imprecise memory is optimized (for a given decision problem and noisy environment) subject to this constraint. We characterize the form of the optimally imprecise memory\, and show that the model implies that both forecasts and actions will exhibit idiosyncratic random variation; that beliefs will fluctuate forever around the rational-expectations (perfect-memory) beliefs with a variance that does not fall to zero; and that more recent news will be given disproportionate weight. The model provides a simple explanation for a number of features of observed forecast bias in laboratory and field settings. [Joint work with Rava Azeredo da Silveira and Yeji Sung
URL:https://cmsa.fas.harvard.edu/event/2-20-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-022019-791x1024-1.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190207T163000
DTEND;TZID=America/New_York:20190207T173000
DTSTAMP:20260430T092023
CREATED:20240212T101329Z
LAST-MODIFIED:20240514T182948Z
UID:10001963-1549557000-1549560600@cmsa.fas.harvard.edu
SUMMARY:Inference for the Mean
DESCRIPTION:Speaker: Ulrich Mueller (Princeton) \nTitle: Inference for the Mean \nAbstract: Consider inference about the mean of a population with finite variance\, based on an i.i.d. sample. The usual t-statistic yields correct inference in large samples\, but heavy tails induce poor small sample behavior. This paper combines extreme value theory for the smallest and largest observations with a normal approximation for the t-statistic of a truncated sample to obtain more accurate inference. This alternative approximation is shown to provide a refinement over the standard normal approximation to the full sample t-statistic under more than two but less than three moments\, while the bootstrap does not. Small sample simulations suggest substantial size improvements over the bootstrap.
URL:https://cmsa.fas.harvard.edu/event/2-7-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-020719.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190119T163000
DTEND;TZID=America/New_York:20190119T163000
DTSTAMP:20260430T092023
CREATED:20240212T100703Z
LAST-MODIFIED:20240514T183205Z
UID:10001956-1547915400-1547915400@cmsa.fas.harvard.edu
SUMMARY:Innovation in Cell Phones in the US and China: Who Improves Technology Faster?
DESCRIPTION:Speaker: Richard B. Freeman (Harvard University and NBER) \nTitle: Innovation in Cell Phones in the US and China: Who Improves Technology Faster? \nAbstract: Cell phones are the archetypical modern consumer innovation\, spreading around the world at an incredible pace\, extensively used for connecting people with the Internet and diverse apps. Consumers report spending from 2-5 hours a day at their cell phones\, with 44% of Americans saying “couldn’t go a day without their mobile devices.” Cell phone manufacturers introduce new models regularly\, embodying additional features while other firms produce new applications that increase demand for the phones. Using newly developed data on the prices\, attributes\, and sales of different models in the US and China\, this paper estimates the magnitude of technological change in the phones in the 2000s. It explores the problems of analyzing a product with many interactive attributes in the standard hedonic price regression model and uses Principal Components Regression to reduce dimensionality. The main finding is that technology improved the value of cell phones at comparable rates in the US and China\, despite different market structures and different evaluations of some attributes and brands. The study concludes with a discussion of ways to evaluate the economic surplus created by the cell phones and their contribution to economic well-being.
URL:https://cmsa.fas.harvard.edu/event/1-30-2019-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Screen-Shot-2019-01-29-at-9.16.13-AM.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20190118T083000
DTEND;TZID=America/New_York:20190121T173000
DTSTAMP:20260430T092023
CREATED:20230715T090318Z
LAST-MODIFIED:20241212T192232Z
UID:10000105-1547800200-1548091800@cmsa.fas.harvard.edu
SUMMARY:Geometric Analysis Approach to AI Workshop
DESCRIPTION:Due to inclement weather on Sunday\, the second half of the workshop has been moved forward one day. Sunday and Monday’s talks will now take place on Monday and Tuesday.\nOn January 18-21\, 2019 the Center of Mathematical Sciences and Applications will be hosting a workshop on the Geometric Analysis Approach to AI. \nThis workshop will focus on the theoretic foundations of AI\, especially various methods in Deep Learning. The topics will cover the relationship between deep learning and optimal transportation theory\, DL and information geometry\, DL Learning and information bottle neck and renormalization theory\, DL and manifold embedding and so on. Furthermore\, the recent advancements\, novel methods\, and real world applications of Deep Learning will also be reported and discussed. \nThe workshop will take place from January 18th to January 23rd\, 2019. In the first four days\, from January 18th to January 21\, the speakers will give short courses; On the 22nd and 23rd\, the speakers will give conference representations. This workshop is organized by Xianfeng Gu and Shing-Tung Yau. \nThe workshop will be held in room G10 of the CMSA\, located at 20 Garden Street\, Cambridge\, MA.  \nSpeakers:  \n\nSarah Adel Bargal\, Boston University\nGuy Bresler\, MIT\nTina Eliassi-Rad\, Northeastern\nYun Raymond Fu\, Northeastern\nBrian Kulis\, Boston University\nNa Lei\, Dalian University of Technology\nYi Ma\, UC Berkeley\nMinh Hoai Nguyen\, Stony Brook\nFrancesco Orabona\, Boston University\nCengiz Pehlevan\, Harvard SEAS\nTomaso Poggio\, MIT\nZhiwei Qin\, DiDi Research America\nKate Saenko\, Boston University\nDimitris Samaras\, Stony Brook\nJohannes Schmidt-Hieber\, University of Twente\nSteven Skiena\, Stony Brook\nVivienne Sze\, MIT\nNaftali Tishby\, ICNC\nJiajun Wu\, MIT\nYing Nian Wu\, UCLA\nGangqiang Xia\, Morgan Stanley\nEric Xing\, Carnegie Mellon\nDonghui Yan\, UMass Dartmouth\nAlan Yuille\, Johns Hopkins\nJuhua Zhu\,  Argus
URL:https://cmsa.fas.harvard.edu/event/geometric-analysis-approach-to-ai-workshop/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Event,Workshop
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/Geo-Analysis-Poster-final-e1547584167900.png
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/New_York:20181205T163000
DTEND;TZID=America/New_York:20181205T173000
DTSTAMP:20260430T092023
CREATED:20240213T072513Z
LAST-MODIFIED:20240514T183912Z
UID:10002179-1544027400-1544031000@cmsa.fas.harvard.edu
SUMMARY:Displacement convexity of Boltzmann's entropy characterizes positive energy in general relativity
DESCRIPTION:Speaker: Robert McCann (University of Toronto) \nTitle: Displacement convexity of Boltzmann’s entropy characterizes positive energy in general relativity \nAbstract: Einstein’s theory of gravity is based on assuming that the fluxes of a energy and momentum in a physical system are proportional to a certain variant of the Ricci curvature tensor on a smooth 3+1 dimensional spacetime. The fact that gravity is attractive rather than repulsive is encoded in the positivity properties which this tensor is assumed to satisfy.  Hawking and Penrose (1971) used this positivity of energy to give conditions under which smooth spacetimes must develop singularities. By lifting fractional powers of the Lorentz distance between points on a globally hyperbolic spacetime to probability measures on spacetime events\, we show that the strong energy condition of Hawking and Penrose is equivalent to convexity of the Boltzmann-Shannon entropy along the resulting geodesics of probability measures. This new characterization of the strong energy condition on globally hyperbolic manifolds also makes sense in (non-smooth) metric measure settings\, where it has the potential to provide a framework for developing a theory of gravity which admits certain singularities and can be continued beyond them. It provides a Lorentzian analog of Lott\, Villani and Sturm’s metric-measure theory of lower Ricci bounds\, and hints at new connections linking gravity to the second law of thermodynamics. Preprint available at http://www.math.toronto.edu/mccann/papers/GRO.pdf \n 
URL:https://cmsa.fas.harvard.edu/event/12-05-2018-colloquium/
LOCATION:CMSA\, 20 Garden Street\, Cambridge\, MA\, 02138\, United States
CATEGORIES:Colloquium
ATTACH;FMTTYPE=image/png:https://cmsa.fas.harvard.edu/media/CMSA-Colloquium-120518.png
END:VEVENT
END:VCALENDAR