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Colloquia & Seminars


Current Seminars

  1. Learning seminar on stability conditions: Quadratic differentials as stability conditions III

    Location: MSRI: Baker Board Room
    Speakers: Dylan Allegretti (MSRI - Mathematical Sciences Research Institute)

    This lecture is part 3 of an introduction to the work of Bridgeland and Smith. I will formulate the main theorem identifying stability conditions and quadratic differentials and talk about the relationship between stable objects and finite-length trajectories of quadratic differentials.

    Updated on Sep 19, 2019 12:26 PM PDT
  2. MLA-Graduate Student Seminar: Wave invariants and inverse spectral theory

    Location: MSRI: Simons Auditorium
    Speakers: Amir Vig (University of California, Irvine)

    The wave trace is a distribution on $\mathbb{R}$ given by $\sum_{j = 1}^\infty e^{it \lambda_j}$, where $\lambda_j^2$ are the (positive) eigenvalues of the Laplacian on a compact domain. In general, two linear waves can be superimposed to give another solution to the wave equation. When we add up a bunch of waves at different frequencies, the peak singularities appear at points with substantial constructive interference. On a manifold, the famous ``propagation of singularities” tells us that waves propagate along geodesics, so the constructive interference is most pronounced along orbits which are traversed infinitely often (i.e. periodic orbits). On the trace side of things, this phenomenon is reflected in the Poisson relation, which says that the singular support of the wave trace is contained in the length spectrum (the collection of lengths of all periodic orbits). For planar domains, the geodesic flow is replaced by the billiard (or broken bicharacteristic) flow and we see an interesting connection between geometric, dynamical and spectral properties of the domain. In this talk, we introduce some simple cases of wave trace formulas before discussing recent work on explicit formulas for wave invariants associated to periodic orbits of small rotation number. This involves proving a dynamical theorem on the structure of such orbits and then constructing an explicit oscillatory integral representation, which microlocally approximates the wave propagator in the interior.

    Updated on Sep 20, 2019 02:15 PM PDT

Upcoming Seminars

  1. HDMP - Weekly Seminar (Part 1): Quiver 3-folds in higher rank

    Location: MSRI: Simons Auditorium
    Speakers: Ivan Smith (Center for Mathematical Sciences)

     A tuple of meromorphic differentials on a curve C determines a non-compact Calabi-Yau threefold X which is the total space of a fibration over C with fibres Milnor fibres of type A surface singularities.  In many cases, aspects of the symplectic topology of this threefold are governed by a quiver with relations associated to an ideal triangulation of C. We will explain some of the things we know about this story and some of the many others we don’t.

    Updated on Sep 19, 2019 03:21 PM PDT
  2. HDMP-Weekly Seminar (Part 2): Quadratic differentials and isomonodromic deformations

    Location: MSRI: Simons Auditorium
    Speakers: Tom Bridgeland (University of Sheffield)

    Moduli spaces of meromorphic quadratic differentials can be viewed as spaces of stability conditions on certain triangulated categories defined either as Fukaya categories or via quivers with relations. This abstract point-of-view predicts the existence of further structure on these spaces, namely a bundle of tori equipped with a pencil of connections. In the case of quadratic differentials I will explain how this structure can be described explicitly in terms of isomonodromic families of opers. This is closely related to the paper of Gaiotto, Moore and Neitzke on wall-crossing and the Hitchin system.

    Updated on Sep 19, 2019 03:26 PM PDT
  3. MLA - Weekly Seminar (Part 1): Semiclassical estimates for scattering on the real line

    Location: MSRI: Simons Auditorium
    Speakers: Jacob Shapiro (Australian National University)

    We prove explicit semiclassical resolvent estimates for an integrable potential on the real line. The proof is a comparatively easy case of the spherical energies method, which has been used to prove similar theorems in higher dimensions and in more complicated geometric situations. The novelty in our results lies in the weakness of the assumptions on the potential. This is joint work with Kiril Datchev.

    Updated on Sep 19, 2019 03:07 PM PDT
  4. MLA - Weekly Seminar (Part 2): Short-time existence for the network flow

    Location: MSRI: Simons Auditorium
    Speakers: Mariel Saez Trumper (Pontificia Universidad Católica de Chile)

    The network flow is a system of parabolic differential equations that describes the motion of a family of curves in which each of them evolves under curve-shortening flow. This problem arises naturally in physical phenomena and its solutions present a rich variety of behaviors. 

    The goal of this talk is to describe some properties of this geometric flow and to discuss an alternative proof of short-time existence for non-regular initial conditions. The methods of our proof are based on techniques of geometric microlocal analysis that have been used to understand parabolic problems on spaces with conic singularities. This is joint work with Jorge Lira, Rafe Mazzeo, and Alessandra Pluda.

    Updated on Sep 19, 2019 03:10 PM PDT
  5. MLA - Regular Seminar: Szegö kernels and Toeplitz operators

    Location: MSRI: Simons Auditorium
    Speakers: Alix Deleporte (MSRI - Mathematical Sciences Research Institute)

    Physicists often argue that the "large spin limit" in quantum spin systems (a limit of large dimension of representations of SU(2)) is a semiclassical limit, where one recovers classical dynamics on S^2. Toeplitz quantization allows one to perform quantization on some compact symplectic spaces (such as S^2). In this talk I will explain the motivations and constructions of Toeplitz quantization, and present a recent work of mine on eigenfunction localisation in this context.

    Updated on Sep 19, 2019 03:13 PM PDT
  6. MLA-Graduate Student Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2019 02:41 PM PDT
  7. HDMP - Weekly Seminar (Part 1)

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

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

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:13 PM PDT
  10. MLA - Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:18 PM PDT
  11. MLA - Special Seminar: Inverse problems for non-linear wave equations and artificial microlocal points sources

    Location: MSRI: Simons Auditorium
    Speakers: Matti Lassas (University of Helsinki)

    We consider inverse problems for non-linear wave equations $\square_g u+au^2=f$ in the the space-time $M\times \R$ having the Lorentzian metric $g$. We consider observations in an open subset $V\subset M\times \R$ that is a
    neighbourhood of a time-like curve $\mu$. Also, we consider solutions $u(x,t)$ of the wave equation that are produced by sources $f$ supported in $V$ and assume that these solutions are observed in the same set $V$, that is, we observe $u|_V$. We show that the conformal class of the metric $g$ can be determined in a large domain $W\subset M$ which is the maximal domain wherev signals sent from $V$ can propagate and return back to $V$.

    The inverse problem for the metric $g$ is solved using the method of artificial microlocal point sources. In this method we do not consider the non-linearity as a troublesome perturbation term, but as an effect that aids in solving the problem. The artificial microlocal point sources are created by distorted plane waves the interact non-linearly and produce singularities that are similar to the singularities produced by a point source that would be in the unknown part $W$ of the space time. Note that as the metric is unknown, the non-linear interaction of the waves need to studied without knowing the coefficients of the wave equation. Using thismethod we are able to solve inverse problems for non-linear equations for which the corresponding problem for linear equations is still unsolved.

    The results have been done in collaboration with Xi Chen, Yaroslav Kurylev, Lauri
    Oksanen, Gabriel Paternain, Gunther Uhlmann, and Yiran Wang.
    References:
    [1] Y. Kurylev, M. Lassas, G. Uhlmann: Inverse problems for Lorentzian manifolds
    and non-linear hyperbolic equations. Inventiones Mathematicae 212 (2018), no. 3,
    781-857
    [2] M. Lassas: Inverse problems for linear and non-linear hyperbolic equations.
    Proceedings of International Congress of Mathematicians ICM 2018, Rio de
    Janeiro, Brazil. 2018, Vol III, pp. 3739-3760.
    [3] M. Lassas, G. Uhlmann, Y. Wang: Inverse problems for semilinear wave
    equations on Lorentzian manifolds. Communications in Mathematical Physics 360
    (2018), 555-609.

    [4] X. Chen, M. Lassas, L. Oksanen, G. Paternain: Detection of Hermitian
    connections in wave equations with cubic non-linearity, arXiv:1902.05711.

    [5] Y. Kurylev, M. Lassas, L. Oksanen, G. Uhlmann: Inverse problem for Einstein-
    scalar field equations, arXiv:1406.4776.

    Created on Sep 19, 2019 10:42 AM PDT
  12. MLA - Regular Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:35 PM PDT
  13. MLA-Graduate Student Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2019 02:41 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. MLA - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:13 PM PDT
  17. MLA - Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:18 PM PDT
  18. MLA - Regular Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:35 PM PDT
  19. 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
  20. MLA-Graduate Student Seminar

    Location: MSRI: Baker Board Room
    Created on Aug 26, 2019 02:41 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. MLA - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:13 PM PDT
  24. MLA - Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:18 PM PDT
  25. MLA - Regular Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:35 PM PDT
  26. MLA-Graduate Student Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2019 02:41 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. MLA - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:13 PM PDT
  30. MLA - Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:18 PM PDT
  31. MLA - Regular Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:35 PM PDT
  32. MLA-Graduate Student Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2019 02:41 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. MLA - Weekly Seminar (Part 1)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:13 PM PDT
  36. MLA - Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:18 PM PDT
  37. MLA - Regular Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:35 PM PDT
  38. MLA-Graduate Student Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2019 02:41 PM PDT
  39. HDMP - Weekly Seminar (Part 1)

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

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

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:13 PM PDT
  42. MLA - Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:18 PM PDT
  43. MLA - Regular Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:35 PM PDT
  44. MLA-Graduate Student Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2019 02:41 PM PDT
  45. HDMP - Weekly Seminar (Part 1)

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

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

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:13 PM PDT
  48. MLA - Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:18 PM PDT
  49. MLA-Graduate Student Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2019 02:41 PM PDT
  50. HDMP - Weekly Seminar (Part 1)

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

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

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:13 PM PDT
  53. MLA - Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:18 PM PDT
  54. MLA - Regular Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:35 PM PDT
  55. MLA-Graduate Student Seminar

    Location: MSRI: Baker Board Room
    Created on Aug 26, 2019 02:41 PM PDT
  56. HDMP - Weekly Seminar (Part 1)

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

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

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:13 PM PDT
  59. MLA - Weekly Seminar (Part 2)

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:18 PM PDT
  60. MLA - Regular Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 27, 2019 01:35 PM PDT

Past Seminars

  1. Seminar 5-Minute Talks

    Updated on Sep 04, 2019 02:45 PM PDT
  2. Seminar 5-Minute Talks

    Updated on Sep 04, 2019 02:45 PM PDT
  3. Seminar 5-Minute Talks

    Updated on Sep 04, 2019 02:45 PM PDT
  4. Seminar 5-Minute Talks

    Updated on Sep 04, 2019 02:45 PM PDT
There are more then 30 past seminars. Please go to Past seminars to see all past seminars.