Photos of the event can be found on CMSA’s Blog.
Organizers:
* This event is sponsored by CMSA Harvard University.
Monday, March 27
Time  Speaker  Title 
8:30am – 9:00am  Breakfast  
9:00am – 10:00am  Kieron Burke, University of California, Irvine  Background in DFT and electronic structure calculations 
10:00am – 11:00am  Kieron Burke, University of California, Irvine 
The density functionals machines can learn 
11:00am – 12:00pm  Sadasivan Shankar, Harvard University  A few key principles for applying Machine Learning to Materials (or Complex Systems) — Scientific and Engineering Perspectives 
Tuesday, March 28
Time  Speaker  Title 
8:30am – 9:00am  Breakfast  
9:00am – 10:00am  Ryan Adams, Harvard  TBA 
10:00am – 11:00am  Gábor Csányi, University of Cambridge 
Interatomic potentials using machine learning: accuracy, transferability and chemical diversity 
11:00am – 1:00pm  Lunch Break  
1:00pm – 2:00pm  Evan Reed, Stanford University  TBA 
Wednesday, March 29
Time  Speaker  Title 
8:30am – 9:00am  Breakfast  
9:00am – 10:00am  Patrick Riley, Google  The Message Passing Neural Network framework and its application to molecular property prediction 
10:00am – 11:00am  Jörg Behler, University of Göttingen  TBA 
11:00am – 12:00pm  Ekin Doğuş Çubuk, Stanford Univers  TBA 
4:00pm  Leslie Greengard, Courant Institute  Inverse problems in acoustic scattering and cryoelectron microscopy
CMSA Colloquium 
Thursday, March 30
Time  Speaker  Title 
8:30am – 9:00am  Breakfast  
9:00am – 10:00am  Matthias Rupp, Fitz Haber Institute of the Max Planck Society  TBA 
10:00am – 11:00am  Petros Koumoutsakos, Radcliffe Institute for Advanced Study, Harvard  TBA 
11:00am – 1:00pm  Lunch Break  
1:00pm – 2:00pm  Dennis Sheberla, Harvard University  Rapid discovery of functional molecules by a highthroughput virtual screening 
Registration and additional information on the conference can be found at http://abel.harvard.edu/jdg/index.html.
Confirmed Speakers
* This event is cosponsored by Lehigh University and partially supported by the National Science Foundation.
]]>This event is open and free. If you would like to attend, please register here to help us keep a headcount. A list of lodging options convenient to the Center can also be found on our recommended lodgings page.
Speakers:
Orr Ashenberg, Fred Hutchinson Cancer Research Center
John Barton, Massachusetts Institute of Technology
Simona Cocco, Laboratoire de Physique Statistique de l’ENS
Sean Eddy, Harvard University
Efthimios Kaxiras, Harvard University
Michael Laub, Massachusetts Institute of Technology
Debora S. Marks, Harvard University
Govind Menon, Brown University
Rémi Monasson, Laboratoire de Physique Théorique de l’ENS
Andrew Murray, Harvard University
Ilya Nemenman, Emory College
Chris Sander, DanaFarber Cancer Institute, Harvard Medical School
Dave Thirumalai, University of Texas at Austin
Martin Weigt, IBPS, Université Pierre et Marie Curie
Matthieu Wyart, EPFL
More speakers will be confirmed soon.
May 1, Monday
Time  Speaker  Topic 
9:0010:00am  Sean Eddy  TBA 
10:0011:00am  Mike Laub  TBA 
11:00am12:00pm  Ilya Nemenman  TBA 
Time  Speaker  Topic 
9:0010:00am  Orr Ashenberg  TBA 
10:0011:00am  Debora Marks  TBA 
11:00am12:00pm  Martin Weigt  TBA 
4:30pm5:30pm  Simona Cocco  CMSA Colloquia 
Time  Speaker  Topic 
9:0010:00am  Andrew Murray  TBA 
10:0011:00am  Matthieu Wyart  TBA 
11:00am12:00pm  Rémi Monasson  TBA 
Time  Speaker  Topic 
9:0010:00am  David Thirumalai  TBA 
10:0011:00am  Chris Sander  TBA 
11:00am12:00pm  John Barton  TBA 
Organizers:
Michael Brenner, Lucy Colwell, Elena Rivas, Eugene Shakhnovich
* This event is sponsored by CMSA Harvard University.
The Center of Mathematic Sciences and Applications will host a conference on From Algebraic Geometry to Vision and AI: A Symposium Celebrating the Mathematical Work of David Mumford. The event will be held in the Harvard Science Center, Hall D.
For a list of lodging options convenient to the Center, please visit our recommended lodgings page.
Confirmed speakers and panelists:
*This event is jointly supported by the CMSA, National Science Foundation, and the International Science Foundation of Cambridge.
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Confirmed speakers:
The conference is coorganized by Denis Auroux and Victor Guillemin. Additional information on the conference will be announced closer to the event.
Time  Speaker  Topic 
8:30am – 9:0am  Breakfast  
9:00am – 10:00am  Jonathan Weitsman  Title: On the geometric quantization of (some) Poisson manifolds 
10:30am – 11:30am  Eckhard Meinrenken  Title: On Hamiltonian loop group spaces
Abstract: Let G be a compact Lie group. We explain a construction of an LGequivariant spinor module over any Hamiltonian loop group space with proper moment map. It may be regarded as its `canonical spinc structure’. We show how to reduce to finite dimensions, resulting in actual spins structure on transversals, as well as twisted spinc structures for the associated quasihamiltonian space. This is based on joint work with Yiannis Loizides and Yanli Song. 
11:30am – 1:30pm  Break  
1:30pm – 2:30pm  Ana Rita Pires  Title: Infinite staircases in symplectic embedding problems
Abstract: McDuff and Schlenk studied an embedding capacity function, which describes when a 4dimensional ellipsoid can symplectically embed into a 4ball. The graph of this function includes an infinite staircase related to the odd index Fibonacci numbers. Infinite staircases have been shown to exist also in the graphs of the embedding capacity functions when the target manifold is a polydisk or the ellipsoid E(2,3). I will describe how we use ECH capacities, lattice point counts and Ehrhart theory to show that infinite staircases exist for these and a few other target manifolds, as well as to conjecture that these are the only such target manifolds. This is a joint work with CristofaroGardiner, Holm and Mandini. 
3:00pm – 4:00pm  Sobhan Seyfaddini  Title: Rigidity of conjugacy classes in groups of areapreserving homeomorphisms
Abstract: Motivated by understanding the algebraic structure of groups of areapreserving homeomorphims F. Beguin, S. Crvoisier, and F. Le Roux were lead to the following question: Can the conjugacy class of a Hamiltonian homeomorphism be dense? We will show that one can rule out existence of dense conjugacy classes by simply counting fixed points. This is joint work with Le Roux and Viterbo. 
4:30pm – 5:30pm  Roger Casals  Title: Differential Algebra of Cubic Graphs Abstract: In this talk we will associate a combinatorial dgalgebra to a cubic planar graph. This algebra is defined by counting binary sequences, which we introduce, and we shall provide explicit computations and examples. From there we study the Legendrian surfaces behind these constructions, including Legendrian surgeries, the count of Morse flow trees involved in contact homology, and the relation to microlocal sheaves. Time permitting, I will explain a connection to spectral networks.Video 
June 6, Tuesday (Full day)
Time  Speaker  Topic 
8:30am – 9:00am  Breakfast  
9:00am – 10:00am  Alejandro Uribe  Title: Semiclassical wave functions associated with isotropic submanifolds of phase space
Abstract: After reviewing fundamental ideas on the quantumclassical correspondence, I will describe how to associate spaces of semiclassical wave functions to isotropic submanifolds of phase space satisfying a BohrSommerfeld condition. Such functions have symbols that are symplectic spinors, and they satisfy a symbol calculus under the action of quantum observables. This is the semiclassical version of the Hermite distributions of Boutet the Monvel and Guillemin, and it is joint work with Victor Guillemin and Zuoqin Wang. I will inlcude applications and open questions. 
10:30am – 11:30am  Alisa Keating  Title: Symplectomorphisms of exotic discs
Abstract: It is a theorem of Gromov that the group of compactly supported symplectomorphisms of R^4, equipped with the standard symplectic form, is contractible. While nothing is known in higher dimensions for the standard symplectic form, we show that for some exotic symplectic forms on R^{4n}, for all but finitely n, there exist compactly supported symplectomorphisms that are smoothly nontrivial. The principal ingredients are constructions of Milnor and Munkres, a symplectic and contact version of the Gromoll filtration, and Borman, Eliashberg and Murphy’s work on existence of overtwisted contact structures. Joint work with Roger Casals and Ivan Smith. 
11:30am – 1:30pm  Break  
1:30pm – 2:30pm  Chen He  Title: Morse theory on bsymplectic manifolds
Abstract: bsymplectic (or logsymplectic) manifolds are Poisson manifolds equipped with symplectic forms of logarithmic singularity. Following Guillemin, Miranda, Pires and Scott’s introduction of Hamiltonian group actions on bsymplectic manifolds, we will survey those classical results of Hamiltonian geometry to the bsymplectic case. 
3:00pm – 4:00pm  Yael Karshon  Title: Geometric quantization with metaplecticc structures
Abstract: I will present a variant of the KostantSouriau geometric quantization procedure that uses metaplecticc structures to incorporate the “half form correction” into the prequantization stage. This goes back to the late 1970s but it is not widely known and it has the potential to generalize and improve upon recent works on geometric quantization. 
The Big Data Conference features 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. This is the third conference on Big Data the Center will host as part of our annual events, and is coorganized by Richard Freeman, Scott Kominers, Jun Liu, HorngTzer Yau and ShingTung Yau.
To register for this event, please click here. For a list of lodging options convenient to the Center, please visit our recommended lodgings page.
Please note that lunch will not be provided during the conference, but a map of Harvard Square with a list of local restaurants can be found by clicking Map & Restaurants.
Confirmed Speakers:
Following the conference, there will be a twoday workshop from August 2021. The workshop is organized by Scott Kominers, and will feature:
Conference Schedule
A PDF version of the schedule below can also be downloaded here.
Time  Speaker  Topic 
8:30 am – 9:00 am  Breakfast  
9:00 am – 9:40 am  Mohammad Akbarpour  Title: Information aggregation in overlapping generations and the emergence of experts
Abstract: We study a model of social learning with “overlapping generations”, where agents meet others and share data about an underlying state over time. We examine under what conditions the society will produce individuals with precise knowledge about the state of the world. There are two information sharing regimes in our model: Under the full information sharing technology, individuals exchange the information about their point estimates of an underlying state, as well as their sources (or the precision of their signals) and update their beliefs by taking a weighted average. Under the limited information sharing technology, agents only observe the information about the point estimates of those they meet, and update their beliefs by taking a weighted average, where weights can depend on the sequence of meetings, as well as the labels. Our main result shows that, unlike most social learning settings, using such linear learning rules do not guide the society (or even a fraction of its members) to learn the truth, and having access to, and exploiting knowledge of the precision of a source signal are essential for efficient social learning (joint with Amin Saberi & Ali Shameli). 
9:40 am – 10:20 am  Lucas Janson  Title: ModelFree Knockoffs For HighDimensional Controlled Variable Selection
Abstract: Many contemporary largescale applications involve building interpretable models linking a large set of potential covariates to a response in a nonlinear fashion, such as when the response is binary. Although this modeling problem has been extensively studied, it remains unclear how to effectively control the fraction of false discoveries even in highdimensional logistic regression, not to mention general highdimensional nonlinear models. To address such a practical problem, we propose a new framework of modelfree knockoffs, which reads from a different perspective the knockoff procedure (Barber and Candès, 2015) originally designed for controlling the false discovery rate in linear models. The key innovation of our method is to construct knockoff variables probabilistically instead of geometrically. This enables modelfree knockoffs to deal with arbitrary (and unknown) conditional models and any dimensions, including when the dimensionality p exceeds the sample size n, while the original knockoffs procedure is constrained to homoscedastic linear models with n greater than or equal to p. Our approach requires the design matrix be random (independent and identically distributed rows) with a covariate distribution that is known, although we show our procedure to be robust to unknown/estimated distributions. As we require no knowledge/assumptions about the conditional distribution of the response, we effectively shift the burden of knowledge from the response to the covariates, in contrast to the canonical modelbased approach which assumes a parametric model for the response but very little about the covariates. To our knowledge, no other procedure solves the controlled variable selection problem in such generality, but in the restricted settings where competitors exist, we demonstrate the superior power of knockoffs through simulations. Finally, we apply our procedure to data from a casecontrol study of Crohn’s disease in the United Kingdom, making twice as many discoveries as the original analysis of the same data. 
10:20 am – 10:50 am  Break  
10:50 pm – 11:30 pm  Noureddine El Karoui  Title: Random matrices and highdimensional statistics: beyond covariance matrices
Abstract: Random matrices have played a central role in understanding very important statistical methods linked to covariance matrices (such as Principal Components Analysis, Canonical Correlation Analysis etc…) for several decades. In this talk, I’ll show that one can adopt a randommatrixinspired point of view to understand the performance of other widely used tools in statistics, such as Mestimators, and very common methods such as the bootstrap. I will focus on the highdimensional case, which captures well the situation of “moderately” difficult statistical problems, arguably one of the most relevant in practice. In this setting, I will show that random matrix ideas help upend conventional theoretical thinking (for instance about maximum likelihood methods) and highlight very serious practical problems with resampling methods. 
11:30 am – 12:10 pm  Nikhil Naik  Title: Understanding Urban Change with Computer Vision and Streetlevel Imagery
Abstract: Which neighborhoods experience physical improvements? In this work, we introduce a computer vision method to measure changes in the physical appearances of neighborhoods from timeseries streetlevel imagery. We connect changes in the physical appearance of five US cities with economic and demographic data and find three factors that predict neighborhood improvement. First, neighborhoods that are densely populated by collegeeducated adults are more likely to experience physical improvements. Second, neighborhoods with better initial appearances experience, on average, larger positive improvements. Third, neighborhood improvement correlates positively with physical proximity to the central business district and to other physically attractive neighborhoods. Together, our results illustrate the value of using computer vision methods and streetlevel imagery to understand the physical dynamics of cities. (Joint work with Edward L. Glaeser, Cesar A. Hidalgo, Scott Duke Kominers, and Ramesh Raskar.) 
12:10 pm – 12:25 pm  Data Science Lightning Talks  
12:25 pm – 1:30 pm  Lunch  
1:30 pm – 2:10 pm  Tracy Ke  Title: A new SVD approach to optimal topic estimation
Abstract: In the probabilistic topic models, the quantity of interest—a lowrank matrix consisting of topic vectors—is hidden in the text corpus matrix, masked by noise, and Singular Value Decomposition (SVD) is a potentially useful tool for learning such a lowrank matrix. However, the connection between this lowrank matrix and the singular vectors of the text corpus matrix are usually complicated and hard to spell out, so how to use SVD for learning topic models faces challenges. We overcome the challenge by revealing a surprising insight: there is a lowdimensional simplex structure which can be viewed as a bridge between the lowrank matrix of interest and the SVD of the text corpus matrix, and which allows us to conveniently reconstruct the former using the latter. Such an insight motivates a new SVDbased approach to learning topic models. For asymptotic analysis, we show that under a popular topic model (Hofmann, 1999), the convergence rate of the l1error of our method matches that of the minimax lower bound, up to a multilogarithmic term. In showing these results, we have derived new elementwise bounds on the singular vectors and several large deviation bounds for weakly dependent multinomial data. Our results on the convergence rate and asymptotical minimaxity are new. We have applied our method to two data sets, Associated Process (AP) and Statistics Literature Abstract (SLA), with encouraging results. In particular, there is a clear simplex structure associated with the SVD of the data matrices, which largely validates our discovery. 
2:10 pm – 2:50 pm  AlbertLászló Barabási  Title: Taming Complexity: From Network Science to Controlling Networks
Abstract: The ultimate proof of our understanding of biological or technological systems is reflected in our ability to control them. While control theory offers mathematical tools to steer engineered and natural systems towards a desired state, we lack a framework to control complex selforganized systems. Here we explore the controllability of an arbitrary complex network, identifying the set of driver nodes whose timedependent control can guide the system’s entire dynamics. We apply these tools to several real networks, unveiling how the network topology determines its controllability. Virtually all technological and biological networks must be able to control their internal processes. Given that, issues related to control deeply shape the topology and the vulnerability of real systems. Consequently unveiling the control principles of real networks, the goal of our research, forces us to address series of fundamental questions pertaining to our understanding of complex systems.

2:50 pm – 3:20 pm  Break  
3:20 pm – 4:00 pm  Marena Lin  Title: Optimizing climate variables for human impact studies
Abstract: Estimates of the relationship between climate variability and socioeconomic outcomes are often limited by the spatial resolution of the data. As studies aim to generalize the connection between climate and socioeconomic outcomes across countries, the best available socioeconomic data is at the national level (e.g. food production quantities, the incidence of warfare, averages of crime incidence, gender birth ratios). While these statistics may be trusted from government censuses, the appropriate metric for the corresponding climate or weather for a given year in a country is less obvious. For example, how do we estimate the temperatures in a country relevant to national food production and therefore food security? We demonstrate that highresolution spatiotemporal satellite data for vegetation can be used to estimate the weather variables that may be most relevant to food security and related socioeconomic outcomes. In particular, satellite proxies for vegetation over the African continent reflect the seasonal movement of the Intertropical Convergence Zone, a band of intense convection and rainfall. We also show that agricultural sensitivity to climate variability differs significantly between countries. This work is an example of the ways in which insitu and satellitebased observations are invaluable to both estimates of future climate variability and to continued monitoring of the earthhuman system. We discuss the current state of these records and potential challenges to their continuity. 
4:00 pm – 4:40 pm  Alex Peysakhovich  Title: Building a cooperator
Abstract: A major goal of modern AI is to construct agents that can perform complex tasks. Much of this work deals with single agent decision problems. However, agents are rarely alone in the world. In this talk I will discuss how to combine ideas from deep reinforcement learning and game theory to construct artificial agents that can communicate, collaborate and cooperate in productive positive sum interactions. 
4:40 pm – 5:20 pm  Tze Leung Lai  Title: Gradient boosting: Its role in big data analytics, underlying mathematical theory, and recent refinements
Abstract: We begin with a review of the history of gradient boosting, dating back to the LMS algorithm of Widrow and Hoff in 1960 and culminating in Freund and Schapire’s AdaBoost and Friedman’s gradient boosting and stochastic gradient boosting algorithms in the period 19992002 that heralded the big data era. The role played by gradient boosting in big data analytics, particularly with respect to deep learning, is then discussed. We also present some recent work on the mathematical theory of gradient boosting, which has led to some refinements that greatly improves the convergence properties and prediction performance of the methodology. 
Time  Speaker  Topic 
8:30 am – 9:00 am  Breakfast  
9:00 am – 9:40 am  Natesh Pillai  Title: Accelerating MCMC algorithms for Computationally Intensive Models via Local Approximations
Abstract: We construct a new framework for accelerating Markov chain Monte Carlo in posterior sampling problems where standard methods are limited by the computational cost of the likelihood, or of numerical models embedded therein. Our approach introduces local approximations of these models into the Metropolis–Hastings kernel, borrowing ideas from deterministic approximation theory, optimization, and experimental design. Previous efforts at integrating approximate models into inference typically sacrifice either the sampler’s exactness or efficiency; our work seeks to address these limitations by exploiting useful convergence characteristics of local approximations. We prove the ergodicity of our approximate Markov chain, showing that it samples asymptotically from the exact posterior distribution of interest. We describe variations of the algorithm that employ either local polynomial approximations or local Gaussian process regressors. Our theoretical results reinforce the key observation underlying this article: when the likelihood has some local regularity, the number of model evaluations per Markov chain Monte Carlo (MCMC) step can be greatly reduced without biasing the Monte Carlo average. Numerical experiments demonstrate multiple orderofmagnitude reductions in the number of forward model evaluations used in representative ordinary differential equation (ODE) and partial differential equation (PDE) inference problems, with both synthetic and real data. 
9:40 am – 10:20 am  Ravi Jagadeesan  Title: Designs for estimating the treatment effect in networks with interference
Abstract: In this paper we introduce new, easily implementable designs for drawing causal inference from randomized experiments on networks with interference. Inspired by the idea of matching in observational studies, we introduce the notion of considering a treatment assignment as a quasicoloring” on a graph. Our idea of a perfect quasicoloring strives to match every treated unit on a given network with a distinct control unit that has identical number of treated and control neighbors. For a wide range of interference functions encountered in applications, we show both by theory and simulations that the classical Neymanian estimator for the direct effect has desirable properties for our designs. This further extends to settings where homophily is present in addition to interference. 
10:20 am – 10:50 am  Break  
10:50 am – 11:30 am  Annie Liang  Title: The Theory is Predictive, but is it Complete? An Application to Human Generation of Randomness
Abstract: When we test a theory using data, it is common to focus on correctness: do the predictions of the theory match what we see in the data? But we also care about completeness: how much of the predictable variation in the data is captured by the theory? This question is difficult to answer, because in general we do not know how much “predictable variation” there is in the problem. In this paper, we consider approaches motivated by machine learning algorithms as a means of constructing a benchmark for the best attainable level of prediction. We illustrate our methods on the task of predicting humangenerated random sequences. Relative to a theoretical machine learning algorithm benchmark, we find that existing behavioral models explain roughly 15 percent of the predictable variation in this problem. This fraction is robust across several variations on the problem. We also consider a version of this approach for analyzing field data from domains in which human perception and generation of randomness has been used as a conceptual framework; these include sequential decisionmaking and repeated zerosum games. In these domains, our framework for testing the completeness of theories provides a way of assessing their effectiveness over different contexts; we find that despite some differences, the existing theories are fairly stable across our field domains in their performance relative to the benchmark. Overall, our results indicate that (i) there is a significant amount of structure in this problem that existing models have yet to capture and (ii) there are rich domains in which machine learning may provide a viable approach to testing completeness (joint with Jon Kleinberg and Sendhil Mullainathan). 
11:30 am – 12:10 pm  Zak Stone  Title: TensorFlow: Machine Learning for Everyone
Abstract: We’ve witnessed extraordinary breakthroughs in machine learning over the past several years. What kinds of things are possible now that weren’t possible before? How are opensource platforms like TensorFlow and hardware platforms like GPUs and Cloud TPUs accelerating machine learning progress? If these tools are new to you, how should you get started? In this session, you’ll hear about all of this and more from Zak Stone, the Product Manager for TensorFlow on the Google Brain team. 
12:10 pm – 1:30 pm  Lunch  
1:30 pm – 2:10 pm  Jann Spiess  Title: (Machine) Learning to Control in Experiments
Abstract: Machine learning focuses on highquality prediction rather than on (unbiased) parameter estimation, limiting its direct use in typical program evaluation applications. Still, many estimation tasks have implicit prediction components. In this talk, I discuss accounting for controls in treatment effect estimation as a prediction problem. In a canonical linear regression framework with highdimensional controls, I argue that OLS is dominated by a natural shrinkage estimator even for unbiased estimation when treatment is random; suggest a generalization that relaxes some parametric assumptions; and contrast my results with that for another implicit prediction problem, namely the first stage of an instrumental variables regression. 
2:10 pm – 2:50 pm  Bradly Stadie  Title: Learning to Learn Quickly: OneShot Imitation and Meta Learning
Abstract: Many reinforcement learning algorithms are bottlenecked by data collection costs and the brittleness of their solutions when faced with novel scenarios. 
2:50 pm – 3:20 pm  Break  
3:20 pm – 4:00 pm  HauTieng Wu  Title: When Medical Challenges Meet Modern Data Science
Abstract: Adaptive acquisition of correct features from massive datasets is at the core of modern data analysis. One particular interest in medicine is the extraction of hidden dynamics from a single observed time series composed of multiple oscillatory signals, which could be viewed as a singlechannel blind source separation problem. The mathematical and statistical problems are made challenging by the structure of the signal which consists of nonsinusoidal oscillations with time varying amplitude/frequency, and by the heteroscedastic nature of the noise. In this talk, I will discuss recent progress in solving this kind of problem by combining the cepstrumbased nonlinear timefrequency analysis and manifold learning technique. A particular solution will be given along with its theoretical properties. I will also discuss the application of this method to two medical problems – (1) the extraction of a fetal ECG signal from a single lead maternal abdominal ECG signal; (2) the simultaneous extraction of the instantaneous heart/respiratory rate from a PPG signal during exercise; (3) (optional depending on time) an application to atrial fibrillation signals. If time permits, the clinical trial results will be discussed. 
4:00 pm – 4:40 pm  Sifan Zhou  Title: Citing People Like Me: Homophily, Knowledge Spillovers, and Continuing a Career in Science
Abstract: Forward citation is widely used to measure the scientific merits of articles. This research studies millions of journal article citation records in life sciences from MEDLINE and finds that authors of the same gender, the same ethnicity, sharing common collaborators, working in the same institution, or being geographically close are more likely (and quickly) to cite each other than predicted by their proportion among authors working on the same research topics. This phenomenon reveals how social and geographic distances influence the quantity and speed of knowledge spillovers. Given the importance of forward citations in academic evaluation system, citation homophily potentially put authors from minority group at a disadvantage. I then show how it influences scientists’ chances to survive in the academia and continue publishing. Based on joint work with Richard Freeman. 
To view photos and video interviews from the conference, please visit the CMSA blog.
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The topic of the talks are as follows:
Date  Title  Abstract 
332017  Modularity of DT invariants on smooth K3 fibrations I  Motivated by Sduality modularity conjectures in string theory, we study the DonaldsonThomas invariants of 2dimensional sheaves inside a nonsingular threefold X. Our main case of study is when X is given by a smooth surface fibration over a curve with the canonical bundle of X pulled back from the base curve. We study the DonaldsonThomas invariants, as defined by Richard Thomas, of the 2dimensional Gieseker stable sheaves in X supported on the fibers. In case whereXis aK3 fibration, analogous to the GromovWitten theory formula established by MaulikPandharipande, we express these invariants in terms of the Euler characteristic of the Hilbert scheme of points on the fiber and the NoetherLefschetz numbers of the fibration, and prove that the invariants have modular properties. We are intending to go through these lectures with a relatively slow speed, that is: TheoremProof style, (so we will be less handwavy!) and we intend to establish some of the required background, e.g NoetherLefschetz theory, vector valuedmodular forms etc. 
382017  Modularity of DT invariants on smooth K3 fibrations II  Motivated by Sduality modularity conjectures in string theory, we study the DonaldsonThomas invariants of 2dimensional sheaves inside a nonsingular threefold X. Our main case of study is when X is given by a smooth surface fibration over a curve with the canonical bundle of X pulled back from the base curve. We study the DonaldsonThomas invariants, as defined by Richard Thomas, of the 2dimensional Gieseker stable sheaves in X supported on the fibers. In case whereXis aK3 fibration, analogous to the GromovWitten theory formula established by MaulikPandharipande, we express these invariants in terms of the Euler characteristic of the Hilbert scheme of points on the fiber and the NoetherLefschetz numbers of the fibration, and prove that the invariants have modular properties. We are intending to go through these lectures with a relatively slow speed, that is: TheoremProof style, (so we will be less handwavy!) and we intend to establish some of the required background, e.g NoetherLefschetz theory, vector valued modular forms etc. 
3102017  Conifold Transitions and modularity of DT invariants on Nodal fibrations 
Following lectures I and II we continue the discussion on the moduli space of shaves with two dimensional support on K3fibered threefolds, which can admit finitely many nodal (rational double point singularity at worst) fibers. We will use the conifold transitions and degeneration techniques in this case to relate the geometry of our moduli space and its enumerative invariants to the ones studied in lectures I, II over smooth K3fibrations.

452017  Stable pair PT invariants on smooth fibrations I  We study PandharipandeThomas’s stable pair theory on smooth K3 fibrations over curves with possibly nodal fibers. We describe stable pair invariants of the fiberwise irreducible curve classes in terms of KawaiYoshioka’s formula for the Euler characteristics of moduli spaces of stable pairs on K3 surfaces and NoetherLefschetz numbers of the fibration. 
472017  Stable pair PT invariants on smooth fibrations II

We study PandharipandeThomas’s stable pair theory on smooth K3 fibrations over curves with possibly nodal fibers. We describe stable pair invariants of the fiberwise irreducible curve classes in terms of KawaiYoshioka’s formula for the Euler characteristics of moduli spaces of stable pairs on K3 surfaces and NoetherLefschetz numbers of the fibration. 
4122017  Stable pair PT invariants on nodal fibrations: perverse sheaves, Wallcrossings, and an analog of fiberwise Tduality  Following lecture 4, we continue the study of stable pair invariants of K3fibered threefolds., We investigate the relation of these invariants with the perverse (noncommutative) stable pair invariants of the K3fibration. In the case that the fibration is a projective CalabiYau threefold, by means of wallcrossing techniques, we write the stable pair invariants in terms of the generalized DonaldsonThomas invariants of 2dimensional Gieseker semistable sheaves supported on the fibers. 
4142017  DT versus MNOP invariants and S_duality conjecture on general complete intersections  Motivated by Sduality modularity conjectures in string theory, we define new invariants counting a restricted class of twodimensional torsion sheaves, enumerating pairs Z⊂H in a Calabi–Yau threefold X. Here H is a member of a sufficiently positive linear system and Z is a onedimensional subscheme of it. The associated sheaf is the ideal sheaf of Z⊂H, pushed forward to X and considered as a certain Joyce–Song pair in the derived category of X. We express these invariants in terms of the MNOP invariants of X. 
4192017  Proof of Sduality conjecture on quintic threefold I  I will talk about an algebraicgeometric proof of the Sduality conjecture in superstring theory, made formerly by physicists Gaiotto, Strominger, Yin, regarding the modularity of DT invariants of sheaves supported on hyperplane sections of the quintic CalabiYau threefold. We use degeneration and localization techniques to reduce the threefold theory to a certain intersection theory over the relative Hilbert scheme of points on surfaces and then prove modularity. More precisely, we have proven that the generating series, associated to the top intersection numbers of the Hilbert scheme of points, relative to an effective divisor, on a smooth quasiprojective surface is a modular form. This is a generalization of the result of OkounkovCarlsson, where they used representation theory and the machinery of vertex operators to prove this statement for absolute Hilbert schemes. These intersection numbers eventually, together with the generating series of NoetherLefschetz numbers as I will explain, will provide the ingredients to achieve an algebraicgeometric proof of Sduality modularity conjecture. 
4282017  Proof of Sduality conjecture on Quintic threefold II  I will talk about an algebraicgeometric proof of the Sduality conjecture in superstring theory, made formerly by physicists Gaiotto, Strominger, Yin, regarding the modularity of DT invariants of sheaves supported on hyperplane sections of the quintic CalabiYau threefold. We use degeneration and localization techniques to reduce the threefold theory to a certain intersection theory over the relative Hilbert scheme of points on surfaces and then prove modularity. More precisely, we have proven that the generating series, associated to the top intersection numbers of the Hilbert scheme of points, relative to an effective divisor, on a smooth quasiprojective surface is a modular form. This is a generalization of the result of OkounkovCarlsson, where they used representation theory and the machinery of vertex operators to prove this statement for absolute Hilbert schemes. These intersection numbers eventually, together with the generating series of NoetherLefschetz numbers as I will explain, will provide the ingredients to achieve an algebraicgeometric proof of Sduality modularity conjecture. 
This workshop will focus on new developments in coding and information theory that sit at the intersection of combinatorics and complexity, and will bring together researchers from several communities — coding theory, information theory, combinatorics, and complexity theory — to exchange ideas and form collaborations to attack these problems.
Squarely in this intersection of combinatorics and complexity, locally testable/correctable codes and listdecodable codes both have deep connections to (and in some cases, direct motivation from) complexity theory and pseudorandomness, and recent progress in these areas has directly exploited and explored connections to combinatorics and graph theory. One goal of this workshop is to push ahead on these and other topics that are in the purview of the yearlong program. Another goal is to highlight (a subset of) topics in coding and information theory which are especially ripe for collaboration between these communities. Examples of such topics include polar codes; new results on ReedMuller codes and their thresholds; coding for distributed storage and for DNA memories; coding for deletions and synchronization errors; storage capacity of graphs; zeroerror information theory; bounds on codes using semidefinite programming; tensorization in distributed source and channel coding; and applications of informationtheoretic methods in probability and combinatorics. All these topics have attracted a great deal of recent interest in the coding and information theory communities, and have rich connections to combinatorics and complexity which could benefit from further exploration and collaboration.
Participation: The workshop is open to participation by all interested researchers, subject to capacity. Click here to register.
Confirmed participants include:
Coorganizers of this workshop include Venkat Guruswami, Alexander Barg, Mary Wootters. More details about this event, including participants, will be updated soon. A list of lodging options convenient to the Center can also be found on our recommended lodgings page.
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