This Week's Talks

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  • Stone-Cech Compactification and Frame Redundancy - RIT on Applied Harmonic Analysis

    Speaker: Radu Balan (UMD) -

    When: Mon, April 16, 2018 - 3:00pm
    Where: Kirwan Hall 1308
  • Far-Field Regularity for the Surface Quasi-Geostrophic (SQG) Equation - RIT on Applied PDE

    Speaker: Fei Wang (University of Maryland) -

    When: Mon, April 16, 2018 - 3:00pm
    Where: Kirwan Hall 1311

    View Abstract

    Abstract: http://www.terpconnect.umd.edu/~lvrmr/2017-2018-S/Classes/RIT.shtml
  • From point-picking to sections of surface bundles - Geometry-Topology

    Speaker: Lei Chen (University of Chicago) - http://math.uchicago.edu/~chenlei/

    When: Mon, April 16, 2018 - 3:15pm
    Where: Kirwan Hall 3206

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    Abstract: Given any n points on a manifold, how can we systematically and continuously find a new point? What if we ask them to be distinct? In this talk, I will try to answer this question in surfaces. Then I will connect this question to sections of surface bundles. The slogan is "there is no center of mass on closed hyperbolic surfaces".
  • The ZX-calculus: Quantum theory with spiders - RIT on Quantum Information

    Speaker: Spencer Breiner (National Institute of Standards and Technology) -

    When: Mon, April 16, 2018 - 4:15pm
    Where: Atlantic 3100A

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    Abstract: In this talk I will give a brief introduction to the ZX-calculus, a formal system of diagrams and graphical manipulations which can be used to give proofs about quantum processes. The first half of the talk will connect the mathematical structures involved--monoidal categories, Frobenius/Hopf algebras--with their physical interpretation in quantum theory. In the remaining time I will demonstrate by example how these methods can help to simplify and clarify quantum analyses.
  • The pro-p-Iwahori-Hecke algebra of a reductive p-adic group (candidacy exam) - Lie Groups and Representation Theory

    Speaker: Yijie Gao

    When: Tue, April 17, 2018 - 2:00pm
    Where: MTH 1310
  • Stable denoising with generative networks - Norbert Wiener Center

    Speaker: Soledad Villar (NYU) -

    When: Tue, April 17, 2018 - 2:00pm
    Where: Kirwan Hall 3206

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    Abstract: It has been experimentally established that deep neural networks can be used to produce good generative models for real world data. It has also been established that such generative models can be exploited to solve classical inverse problems like compressed sensing and super resolution. In this work we focus on the classical signal processing problem of image denoising. We propose a theoretical setting that uses spherical harmonics to identify what mathematical properties of the activation functions will allow signal denoising with local methods.
  • Moduli Space of Dilation Surfaces - Student Dynamics

    Speaker: Jenny Rustad (UMD) -

    When: Tue, April 17, 2018 - 3:15pm
    Where: Kirwan Hall 1310

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    Abstract: I will discuss a paper by Selim Ghaziouani "Teichmuller Dynamics, Dilation Tori and Piecewise Affine Circle Homeomorphisms".
  • Binary sequences and trees in model theory - Logic

    Speaker: Hunter Chase (University of Illinois Chicago) -

    When: Tue, April 17, 2018 - 3:30pm
    Where: Kirwan Hall 1311

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    Abstract: VC-dimension and Shelah's 2-rank (also known as Littlestone or thicket dimension) are important measures of complexity associated with the NIP/IP and stable/unstable dividing lines. We examine these through the lens of binary trees and sequences. We introduce the concept of banned sequence problems as a tool to obtain new proofs of the Sauer-Shelah lemma and some of its variants. We use these results to modestly improve a result of Malliaris and Terry on type trees of stable graphs and prove a new variant of the Sauer-Shelah lemma for the op-rank setting of Guingona and Hill.

    This work is joint with James Freitag.
  • Model Theory Reading Seminar - Student Logic Seminar

    Speaker: Douglas Ulrich (University of Maryland) -

    When: Tue, April 17, 2018 - 3:30pm
    Where: Kirwan Hall 1311
  • Combination, Relevance & Comparability - RIT on Statistics

    Speaker: Paul Smith (STAT Program) -

    When: Tue, April 17, 2018 - 4:00pm
    Where: Kirwan Hall 1313
  • Small random perturbations unlock hyperbolicity - Probability

    Speaker: Alex Blumenthal (UMD) - http://math.umd.edu/~alexb123/

    When: Wed, April 18, 2018 - 11:00am
    Where: Kirwan Hall 3206

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    Abstract: For smooth dynamical systems, hyperbolicity (strong expansion and contraction at infinitesimal level) is the main mechanism by which deterministic dynamical systems have chaotic asymptotic regimes. Uniformly hyperbolic systems, those exhibiting hyperbolicity on all of phase space or on the entirety of a stable attractor, are well-known to be asymptotically chaotic. The hyperbolicity mechanism is quite sensitive, however, in the sense that even for systems which are “mostly” hyperbolic except for a small exceptional set in phase space, the problem of determining the asymptotic regime (chaotic versus `ordered') is notoriously challenging.

    In this talk I will discuss some of the inherent difficulties (coexistence phenomena, cone twisting) in studying “mostly” hyperbolic systems. Then, I will put forward the view that the addition of some IID randomness at each timestep has the effect of “unlocking” hyperbolicity, greatly simplifying the study of these systems. I will discuss results on classes of 1D and 2D models which are “mostly” hyperbolic, including multimodal maps of the circle and the well-studied Chirikov standard map family on the torus.

    This work is joint with Yun Yang, Lai-Sang Young and Jinxin Xue.
  • Moduli spaces of dilation surfaces - Student Geometry and Topology

    Speaker: Jenny Rustad (UMD) -

    When: Wed, April 18, 2018 - 1:00pm
    Where: Kirwan Hall 1310
  • The synchronization problem for Kuramoto oscillators and beyond - CSCAMM

    Speaker: Dr. Javier Morales (CSCAMM, University of Maryland) - https://www2.cscamm.umd.edu/~javierm1/

    When: Wed, April 18, 2018 - 2:00pm
    Where: CSIC 4122

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    Abstract: In this talk, we will review the state of the art for the synchronization problem of the Kuramoto model at the kinetic and particle level. Additionally, we will introduce new developments and variational techniques for the dynamics of this model and some of its variants and generalization.
  • Representation ring of Levi subgroups versus cohomology ring of flag varieties - Lie Groups and Representation Theory

    Speaker: Shrawan Kumar (UNC Chapel Hill) - http://www.unc.edu/math/Faculty/kumar/

    When: Wed, April 18, 2018 - 2:00pm
    Where: Kirwan Hall 1311

    View Abstract

    Abstract: See PDF.
  • "When you need to do both: Coupling Global Optimization and Classification with Bayesian models" - Student AMSC

    Speaker: Graham Antoszewski (University of Maryland - AMSC) -

    When: Wed, April 18, 2018 - 3:00pm
    Where: Kirwan Hall 1310
  • Eigenvalue problem for reductive groups - Colloquium

    Speaker: Shrawan Kumar (UNC at Chapel Hill) - http://www.unc.edu/math/Faculty/kumar/

    When: Wed, April 18, 2018 - 3:15pm
    Where: Kirwan Hall 3206

    View Abstract

    Abstract: See PDF.
  • Deep Learning - now and the future, an overview - RIT on Deep Learning

    Speaker: James Yorke (UMD ) - http://www.chaos.umd.edu/~yorke/

    When: Thu, April 19, 2018 - 10:00am
    Where: Kirwan Hall 3206
  • Asymptotically log del Pezzo surfaces - Algebra-Number Theory

    Speaker: Jesus Martinez-Garcia (University of Bath) - http://people.bath.ac.uk/jmg51/

    When: Thu, April 19, 2018 - 12:00pm
    Where: Kirwan Hall 0401

    View Abstract

    Abstract: Asymptotically log del Pezzo surfaces are a generalisation of del Pezzo surfaces. These surfaces of Fano type are rational and belong to an infinite number of deformation families. Moreover, they are natural candidates for the existence of singular Kaehler-Einstein metrics with conical singularities of large angles along a divisor. Asymptotically log del Pezzo surfaces were introduced by Cheltsov and Rubinstein who classified them under some extra strong condition. We remove the need for an extra condition to give a full classification of these surfaces. This is joint work with Yanir Rubinstein.
  • Turbulence closure ideas from plasma physics - Applied Dynamics

    Speaker: William Dorland - UMD Physics

    When: Thu, April 19, 2018 - 12:30pm
    Where: ERF 1027

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    Abstract: First-principles turbulence simulations are expensive but very useful in many contexts. One approach to improving one's ability to predict experimental or observational data is to design algorithms for ever more processors, allowing ever higher (and more realistic) resolution. But one can also try to work in the opposite direction, developing closures to reduce the resource demands of computations. In a typical high-resolution turbulence simulation that I undertake, there are O(10**9) spectral amplitudes. Only a tiny percentage of these modes are excited to any appreciable level. I will discuss (and seek advice from the audience!) approaches we are pursuing to develop algorithms that solve a closed (or somewhat reduced) first-principles system with as little resolution as should be required.
  • Thermodynamic formalism for some models with countable Markov partitions - Dynamics

    Speaker: Michael Jakobson (UMD) - http://www.math.umd.edu/~jakobson/

    When: Thu, April 19, 2018 - 2:05pm
    Where: Kirwan Hall 1311

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    Abstract: We review several results about ergodic and statistical properties of hyperbolic attractors and present new results obtained in a joint work with Lucia Simonelli (ICTP, Trieste).
  • Mirror symmetry of elliptic curves (cont) - RIT on Geometry and Physics

    Speaker: Freddy Cisneros

    When: Thu, April 19, 2018 - 3:30pm
    Where: Physics Bldg 1117
  • Axioms of Dependence Measures; Energy, Matter, and Mind - Statistics

    Speaker: Gabor Szekely (National Science Foundation) -

    When: Thu, April 19, 2018 - 3:30pm
    Where: Kirwan Hall 1313

    View Abstract

    Abstract: In the past 130 years many dependence measures have been introduced. One of the last ones, distance correlation, was introduced by the speaker in 2005.

    Is there a universally acceptable system of axioms that helps to select the correlation for the 21st century? In this talk we propose four simple axioms for dependence measures and then discuss if classical and new measures of dependences satisfy them. A general framework connects Energy, Matter, and Mind. This is the starting point of a distance based topological data analysis.