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All Colloquia & Seminars

Current Seminars

No current seminar

Upcoming Seminars

  1. HDMP - Special Seminar (part 1) - Smooth compactifications of strata of differentials, with examples

    Location: MSRI: Simons Auditorium
    Speakers: Samuel Grushevsky (State University of New York, Stony Brook), Martin Moeller (Johann Wolfgang Goethe-Universität Frankfurt)

    We will describe the geometry of a smooth functorial compactification of the strata. That is, we will describe a compact algebraic variety that parameterizes the data of certain geometric multi-scale differentials, which compactifies the locus of smooth Riemann surfaces together with a differential with prescribed zeroes and poles. The multi-scale differentials are certain collections of meromorphic differentials on the components of nodal Riemann surfaces, together with some extra data. We will describe the general construction and define the objects, and then discuss a few low-dimensional cases in full detail.

    Updated on Aug 22, 2019 01:38 PM PDT
  2. HDMP - Special Seminar (part 2) - Smooth compactifications of strata of differentials, with examples

    Location: MSRI: Simons Auditorium
    Speakers: Samuel Grushevsky (State University of New York, Stony Brook), Martin Moeller (Johann Wolfgang Goethe-Universität Frankfurt)

    We will describe the geometry of a smooth functorial compactification of the strata. That is, we will describe a compact algebraic variety that parameterizes the data of certain geometric multi-scale differentials, which compactifies the locus of smooth Riemann surfaces together with a differential with prescribed zeroes and poles. The multi-scale differentials are certain collections of meromorphic differentials on the components of nodal Riemann surfaces, together with some extra data. We will describe the general construction and define the objects, and then discuss a few low-dimensional cases in full detail.

    Updated on Aug 22, 2019 01:50 PM PDT
  3. MLA - Interactions of Semilinear Conormal Singularities

    Location: MSRI: Simons Auditorium
    Speakers: Antônio Sá Barreto (Purdue University)

    We discuss the propagation of conormal singularities of solutions of  $P(y,D) u= f(y,u),$  $y \in \mathbb{R}^n,$ $n\geq 3,$ where $P(y,D)$ is a second order strictly hyperbolic operator and $f\in C^\infty.$

    Updated on Aug 22, 2019 09:33 AM PDT
  4. HDMP - Weekly Seminar (part 1) - On triply periodic polyhedral surfaces

    Location: MSRI: Simons Auditorium
    Speakers: Dami Lee (University of Washington)

    A classical question in geometry is whether surfaces with given geometric features can be realized as surfaces in Euclidean space. We will investigate surfaces with cone metrics and find concrete examples of triply periodic polyhedra that have identifiable conformal structures.

    Related questions are

    1. How do we come up with examples?

    2. Are there (if so, how many) saddle connections on infinite polyhedra with their natural polyhedral metric? What are their Veech groups?

    3. Furthermore, these examples connect to Novikov’s problem on hyperplane sections. The intersection of a triply periodic polyhedral surface $P$ and a hyperplane $H$ yields one-dimensional curves which are level sets of a 1-form on the surface. Then what can we say about the set $\{\omega H\}$ as we vary $H,$ thinking of it as a subset of the vector space of holomorphic 1-forms on the intersection. In other words, what does the family of translation surfaces look like?

    These questions lie in the intersection of flat geometry and dynamics. It is also known that the motivation for Novikov’s problem comes from physics where periodic surfaces in $\mathbb{R}^3$ are understood as a Fermi surface of some metal, and the plane sections can be explained as a hyperplane orthogonal to the magnetic field.

    In this talk, instead of answering these questions, we will discuss very specific examples of polyhedral surfaces and describe the questions that are asked above.

     

     

    Updated on Aug 23, 2019 11:18 AM PDT
  5. HDMP-Weekly Seminar (part 2) - Bridgeland stability and quadratic differentials

    Location: MSRI: Simons Auditorium
    Speakers: Alex Takeda (University of California, Berkeley)

    This talk will be an introduction to Bridgeland stability conditions on triangulated categories, oriented towards researchers in the field of quadratic differentials. After introducing the definitions and working out some explicit examples of spaces of stability conditions, I will summarize the results of Bridgeland-Smith and Haiden-Katzarkov-Kontsevich, which are two different, but related, appearances of quadratic differentials in the study of stability conditions. Time allowing I will discuss some of my results on the subject.

    Updated on Aug 23, 2019 11:19 AM PDT
  6. MLA - Weekly Seminar (part 1) - Eigenmodes of the Laplacian on Surfaces of Negative Curvature

    Location: MSRI: Simons Auditorium
    Speakers: Stephane Nonnenmacher (Université de Paris XI)

    (joint work with Semyon Dyatlov and Long Jin)

    The eigenmodes of the Laplacian on a smooth compact Riemannian manifold $(M,g)$ can exhibit various localization properties in the high frequency limit, which depend on the properties of the geodesic flow on $(M,g)$. 

    I will focus on a "quantum chaotic" situation, namely assume that the geodesic flow is strongly chaotic (Anosov); this is the case if the sectional curvature of $(M,g)$ is strictly negative. The Quantum Ergodicity theorem then states that almost all eigenmodes become equidistributed on $M$ in the the high-frequency limit. The Quantum Unique Ergodicity conjecture states that this behaviour suffers no exception, namely all eigenstates equidistribute in this limit.

    This conjecture remaining open, a less ambitious goal is to constrain the possible localization behaviours of the eigenmodes. I will report on recent progress in the case of negative curvature surfaces. Generalizing a previous work by Dyatlov-Jin in the constant curvature case, we show that the eigenmodes cannot concentrate on a proper subset of $M$, in the high frequency limit.

    More precisely, any semiclassical measure associated with the sequence of eigenmodes must have full support on $S^*M$. The proof uses the foliation of the phase space into stable and unstable manifolds, methods from semiclassical analysis, and a new Fractal Uncertainty Principle due to Bourgain-Dyatlov, which I will use as a "black box". I plan to describe the strategy of proof in the constant curvature case, and indicate the necessary modifications in the variable curvature setting.

     

    Updated on Aug 23, 2019 11:09 AM PDT
  7. MLA - Weekly Seminar (part 2) - Eigenmodes of the Laplacian on Surfaces of Negative Curvature

    Location: MSRI: Simons Auditorium
    Speakers: Stephane Nonnenmacher (Université de Paris XI)

    (joint work with Semyon Dyatlov and Long Jin)

    The eigenmodes of the Laplacian on a smooth compact Riemannian manifold $(M,g)$ can exhibit various localization properties in the high frequency limit, which depend on the properties of the geodesic flow on $(M,g)$. 

    I will focus on a "quantum chaotic" situation, namely assume that the geodesic flow is strongly chaotic (Anosov); this is the case if the sectional curvature of $(M,g)$ is strictly negative. The Quantum Ergodicity theorem then states that almost all eigenmodes become equidistributed on $M$ in the the high-frequency limit. The Quantum Unique Ergodicity conjecture states that this behaviour suffers no exception, namely all eigenstates equidistribute in this limit.

    This conjecture remaining open, a less ambitious goal is to constrain the possible localization behaviours of the eigenmodes. I will report on recent progress in the case of negative curvature surfaces. Generalizing a previous work by Dyatlov-Jin in the constant curvature case, we show that the eigenmodes cannot concentrate on a proper subset of $M$, in the high frequency limit.

    More precisely, any semiclassical measure associated with the sequence of eigenmodes must have full support on $S^*M$. The proof uses the foliation of the phase space into stable and unstable manifolds, methods from semiclassical analysis, and a new Fractal Uncertainty Principle due to Bourgain-Dyatlov, which I will use as a "black box". I plan to describe the strategy of proof in the constant curvature case, and indicate the necessary modifications in the variable curvature setting.


     

    Updated on Aug 23, 2019 11:11 AM PDT
  8. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  9. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  10. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  11. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  12. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  13. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  14. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  15. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  16. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  17. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  18. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  19. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  20. Microlocal Analysis and Spectral Theory: A Conference in Honor of Richard Melrose

    Location: UC Berkeley Math
    Speakers: Nalini Anantharaman (Université de Strasbourg), Yaiza Canzani (Harvard University), Semyon Dyatlov (University of California, Berkeley), Colin Guillarmou (Université de Paris XI (Paris-Sud)), Victor Guillemin (Massachusetts Institute of Technology), Peter Hintz (Massachusetts Institute of Technology), Gilles Lebeau (Université Nice Sophia-Antipolis), Laure Saint-Raymond, Peter Sarnak (Princeton University), Terence Tao (University of California, Los Angeles), Akshay Venkatesh (Institute for Advanced Study)

    This will be a conference on the wide range of topics aimed to inspire future directions and new applications of microlocal methods. 

    Updated on Jun 18, 2019 01:45 PM PDT
  21. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  22. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  23. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  24. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  25. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  26. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  27. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  28. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  29. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  30. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  31. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  32. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  33. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  34. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT
  35. HDMP - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:35 PM PDT
  36. HDMP-Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 21, 2019 04:38 PM PDT

Past Seminars

  1. Seminar Women at MSRI lunch

    Created on Feb 13, 2019 03:50 PM PST
  2. Seminar Women at MSRI lunch

    Created on Feb 13, 2019 03:50 PM PST
There are more then 30 past seminars. Please go to Past seminars to see all past seminars.