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Colloquia & Seminars


  1. Algebraic K- and L-theory of groups rings and their applications to topology and geometry, Part II: Main Talk

    Location: UC Berkeley, 740 Evans Hall
    Speakers: Wolfgang Lueck

    We give an introduction to the K- and L-theoretic Farrell-Jones Conjecture and discuss its status. e.g, recently it has been proved for all lattices in almost connected Lie groups. We give a panorama of its large variety of applications, for instance to the Novikov Conjecvture about the homotopy invariance of higher signatures, the Borel Conjecture about the
    topological rigidity of aspherical manifolds and to hyperbolic groups with spheres as boundary. Finally we dicsuss some connections to equivariant homotopy and homology for proper actions of infinite groups.

    Created on Apr 14, 2014 11:19 AM PDT
  2. AT Research Seminar: The classification of Taylor towers for functors from based spaces to spectra

    Location: MSRI: Simons Auditorium
    Speakers: Michael Ching (Amherst College)

    The Goodwillie derivatives of a functor from based spaces to spectra possess additional structure that allows the Taylor tower of the functor to be reconstructed. I will describe this structure as a 'module' over the 'pro-operad' formed by the Koszul duals of the little disc operads. For certain functors this structure arises from an actual module over the little L-discs operad for some L. In particular, this is the case for functors that are left Kan extensions from a category of 'pointed framed L-dimensional manifolds' (which are examples of the zero-pointed manifolds of Ayala and Francis). As an application I will describe where Waldhausen's algebraic K-theory of spaces fits into this picture. This is joint work with Greg Arone (and, additionally, with Andrew Blumberg for the application to K-theory).

    Updated on Apr 14, 2014 11:20 AM PDT
  1. Unlikely intersections in semi-abelian schemes.

    Location: 891 Evans Hall
    Speakers: Daniel Bertrand (Universite Paris VI)

    Given a "non-special" section of a semi-abelian scheme over a curve, the relative Manin-Mumford conjecture (RMM) asserts that its image W meets only finitely many torsion curves. I will explain how a relative version of the points constructed (in a Kummer theoretical setting) by the organizer of this seminar  provide ``very special" examples of infinite intersection. However, the corresponding curves W recover a "normally special" status, when viewed in the setting of Pink's conjecture on mixed Shimura varieties. Furthermore, these sections form the only counterexample to the standard version of RMM for semi-abelian surfaces. These are joint results with B. Edixhoven, and with D. Masser, A. Pillay and U. Zannier.

    Created on Apr 11, 2014 02:11 PM PDT
  2. AT Open Problems/Work in Progress Seminar: Problems arising from an interface between homotopy theory and knot theory.

    Location: MSRI: Simons Auditorium
    Speakers: Dev Sinha (University of Oregon)

    I will survey some mathematics around the application of Goodwillie-Weiss Embedding Calculus to knot theory and some then share some related problems.  These problems (and related comments and questions) include:

    - Are the cochains of the n-disks operad formal, say as diagrams of E_infinity algebras?  (This would imply a spectral sequence collapse result, which would in turn imply major results in knot theory and its interface with mathematical physics and Lie theory.  What machinery is there to establish formality of cochains integrally?  Could intersection
    theoretic models serve over the integers some of the roles that differential forms play over the reals?)

    - Can one explicitly and geometrically define invariants of homotopy classes of maps between say finite complexes which are associated to a bar construction on their cochains over the Koszul dual of the E_infty operad (that is, the derivatives of the identity functor)?  (Rationally, such explicit and geometric "homotopy periods" defined using the bar
    construction over the Lie cooperad are a pretty story, useful for applications to geometric questions in which homotopy arises.)

    - What are some other consequences of formality of the disks operad, including a strong version in dimension two?  (This is less my direct interest and more something to bring to the attention of people doing things with these operads, including in calculus and factorization homology.  Some like Kontsevich have gotten quite a lot of mileage from this formality over the reals.)

    To lead up to these questions, I'll start with simple models for the Goodwillie-Weiss tower, inspired by Gauss's definition of linking number.

    Updated on Apr 17, 2014 04:34 PM PDT
  3. Conformal Field Theory

    Location: MSRI: Baker Board Room
    Created on Feb 19, 2014 08:18 AM PST
  4. MSRI/Evans Lecture: A journey through motivic integration

    Location: 60 Evans Hall
    Speakers: François Loeser (Université de Paris VI (Pierre et Marie Curie))

    Motivic integration was invented by Kontsevich about 20 years ago for proving that Hodge numbers of Calabi-Yau are birational invariants and has developed at a fast pace since. I will start by presenting informally a device for defining and computing motivic integrals due to Cluckers and myself. I will then focus on  some recent applications. In particular I plan to explain how motivic integration provides tools for proving uniformity results for $p$-adic integrals occuring in the Langlands program and  how one may use "motivic harmonic analysis" to study certain generating series counting curves in enumerative algebraic geometry.

    Updated on Apr 11, 2014 03:43 PM PDT
  5. Berkeley Topology Seminar: Part II: Main Talk - A variant of Rohlin's Theorem: on eta cubed

    Location: 3 Evans Hall
    Speakers: Michael Hill (University of Virginia)

    Rohlin's theorem on the signature of Spin 4-manifolds can be restated in terms of the connection between real and complex K-theory given by homotopy fixed points. This comes from a bordism result about Real manifolds versus unoriented manifolds, which in turn, comes from a C2-equivariant story. I'll describe a surprising analogue of this for
    larger cyclic 2 groups, showing that the element eta cubed is never detected! In particular, for any bordism theory orienting these generalizations of Real manifolds, the three torus is always a boundary.

    Created on Apr 17, 2014 04:55 PM PDT
  6. AT Research Seminar Pre-Talk: The Dold-Kan correspondence and commutative monoids

    Location: MSRI: Simons Auditorium
    Speakers: Birgit Richter (Universität Hamburg)

    Over a field in characteristic zero commutative dgas are well-behaved; otherwise they are not. For instance there isn't a
    right-induced model structure on them in the general case. I'll explain some of these issues and advertise symmetric sequences to repair that defect.

    Updated on Apr 17, 2014 04:57 PM PDT
  7. AT Research Seminar: An algebraic model for commutative HZ-algebras.

    Location: MSRI: Simons Auditorium
    Speakers: Birgit Richter (Universität Hamburg)

    Eilenberg-Mac Lane spectra represent singular cohomology and they allow for rather algebraic considerations in stable homotopy theory. Shipley proved that there is a Quillen equivalence between algebras over the Eilenberg-Mac Lane spectrum of the integers, HZ, and differential graded rings. I'll talk about ongoing work with her where we aim at extending her result to commutative HZ-algebras. This builds on a Dold-Kan type theorem for commutative monoids in symmetric sequences.

    Updated on Apr 17, 2014 04:58 PM PDT
  8. AT Postdoc Seminar: The Mirror Symmetry Conjecture and Cobordisms

    Location: MSRI: Baker Board Room
    Speakers: Hiro Tanaka (Harvard University)

    This talk--aimed for a general audience of neither topologists nor model theorists--will discuss applications of cobordisms to Kontsevich's mirror symmetry conjecture. We'll begin by stating a rough version of the
    conjecture, which builds a bridge between symplectic geometry on one hand, and on the other hand, algebraic geometry over the complex numbers. We then discuss how the theory of cobordisms, which studies when two manifolds can be the boundary of another manifold, sheds light on how to generalize the mirror symmetry conjecture, while giving us information about objects in symplectic geometry. (For example, two Lagrangians related by a compact cobordism are equivalent in the Fukaya category.)

    Updated on Apr 17, 2014 05:00 PM PDT
  9. MT Postdoc Seminar

    Location: MSRI: Baker Board Room
    Updated on Apr 15, 2014 02:45 PM PDT
  10. Conformal Field Theory

    Location: MSRI: Baker Board Room
    Created on Feb 19, 2014 08:18 AM PST
  11. MSRI/Evans Lecture: The (un)reasonable effectiveness of model theory in mathematics

    Location: 60 Evans Hall
    Speakers: Carol Wood (Wesleyan University)

    The talk will be built around  examples of how model theory informs our understanding in areas of mathematics such as algebra, number theory, algebraic geometry and analysis. The model theory behind these applications includes concepts such as compactness, definability, stability and o-minimality. However, we assume  no special expertise in model theory, but rather aim  to illustrate the kinds  of  mathematical questions for which a model theoretical perspective has proven to be useful.

    Updated on Apr 15, 2014 11:58 AM PDT
  12. Eisenbud Seminar: Algebraic Geometry and Commutative Algebra

    Location: Evans 939

    3:45pm
    Speaker: Zvi Rosen (UC Berkeley)
    Title:   Computing Algebraic Matroids

    Abstract: Algebraic matroids characterize the combinatorial structure of an algebraic variety. By decorating the matroid with circuit polynomials and base degrees, we capture even more information about the variety and its coordinate projections.  In this talk, we will introduce algebraic matroids, discuss algorithms for their computation, and present some motivating examples.

     

    5:00pm
    Speaker: Noah Giansiracusa (UC Berkeley)
    Title:  Equations of Tropical Varieties

    Abstract: I'll discuss joint work with J.H. Giansiracusa (Swansea) in which we study scheme theory over the tropical semiring T, using the notion of semiring schemes provided by Toen-Vaquie, Durov, or Lorscheid. We define tropical hypersurfaces in this setting and a tropicalization functor that sends closed subschemes of a toric variety over a field with non-archimedean valuation to closed subschemes of the corresponding toric variety over T. Upon passing to the set of \mathbb{T}-valued points this yields Kajiwara-Payne's extended tropicalization functor. We prove that the Hilbert polynomial of any projective subscheme is preserved by our tropicalization functor, so the scheme-theoretic foundations developed here reveal a hidden flatness in the degeneration sending a variety to its tropical skeleton.

    Created on Feb 10, 2014 08:42 AM PST
  13. AT Research Seminar

    Location: MSRI: Simons Auditorium
    Created on Feb 14, 2014 08:56 AM PST
  14. MT Postdoc Seminar

    Location: MSRI: Simons Auditorium
    Created on Feb 06, 2014 09:23 AM PST
  15. AT Postdoc Seminar

    Location: MSRI: Simons Auditorium
    Speakers: Vesna Stojanoska (Massachusetts Institute of Technology)
    Created on Feb 07, 2014 09:36 AM PST
  16. Conformal Field Theory

    Location: MSRI: Baker Board Room
    Created on Feb 19, 2014 08:18 AM PST
  17. AT Research Seminar

    Location: MSRI: Simons Auditorium
    Created on Feb 14, 2014 08:57 AM PST
  18. MT Postdoc Seminar

    Location: MSRI: Simons Auditorium
    Created on Feb 06, 2014 09:23 AM PST
  19. AT Postdoc Seminar

    Location: MSRI: Simons Auditorium
    Speakers: Joseph Hirsh (Massachusetts Institute of Technology)
    Created on Feb 07, 2014 09:37 AM PST
  20. AT Seminar

    Location: MSRI: Simons Auditorium
    Speakers: Alexei Kitaev (Kavli Institute for Theoretical Physics)
    Created on Apr 14, 2014 09:17 AM PDT
  21. Conformal Field Theory

    Location: MSRI: Baker Board Room
    Created on Feb 19, 2014 08:23 AM PST
  22. AT Research Seminar

    Location: MSRI: Baker Board Room
    Created on Feb 14, 2014 08:57 AM PST
  23. Conformal Field Theory

    Location: MSRI: Baker Board Room
    Created on Feb 19, 2014 08:24 AM PST
  24. AT Research Seminar

    Location: MSRI: Simons Auditorium
    Created on Feb 14, 2014 08:58 AM PST

Past Seminars

seminar
  1. Seminar MT Postdoc Seminar

    Created on Feb 06, 2014 09:21 AM PST
  2. Seminar MT Basics

    Created on Mar 21, 2014 02:26 PM PDT
There are more then 30 past seminars. Please go to Past seminars to see all past seminars.