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Colloquia & Seminars


Current Seminars

  1. Local rigidity of uniform lattices

    Location: MSRI: Simons Auditorium
    Speakers: Arie Levit (Weizmann Institute of Science)

    A lattice is topologically locally rigid (t.l.r) if small deformations of it are isomorphic lattices. Uniform lattices in Lie groups were shown to be t.l.r by Weil [60']. We show that uniform lattices are t.l.r in any compactly generated topological group G.

    A lattice is locally rigid (l.r) is small deformations arise from conjugation. It is a classical fact due to Weil [62'] that lattices in semi-simple Lie groups are l.r. Relying on our t.l.r results and on recent work by Caprace-Monod we prove l.r for uniform lattices in the isometry groups of proper geodesically complete CAT(0) spaces, with the exception of SL2(R) factors which occurs already in the classical case.

    Moreover we are able to extend certain finiteness results due to Wang to this more general context of CAT(0) groups.

    In the talk I will explain the above notions and results, and present some ideas from the proofs. This is a joint work with Tsachik Geladner.

    Created on Sep 23, 2016 10:44 AM PDT

Upcoming Seminars

  1. Member Seminar: Automorphisms of RAAGs: vast or skimpy?

    Location: MSRI: Simons Auditorium
    Speakers: Vincent Guirardel (Institut de Recherche Mathematique (IRMAR))

    Say that a group G involves all finite groups if for every finite group F, some finite index subgroup of G maps onto F.
    For instance, for n>2, SL_n(Z) does not involve all finite groups, whereas Out(F_n) does for n>1. The family of groups Out(A) of outer automorphisms of right angled Artin groups "interpolates" between SL_n(Z) and Out(F_n), and the goal of this talk is to describe the boundary between these 2 behaviours, within this family of groups. We also study other "vastness" properties like SQ-universality, of having many quasimorphisms, and we prove that the boundary happens to be the same. This is a joint work with Andrew Sale.

    Updated on Sep 14, 2016 10:13 AM PDT
  2. Working Seminar: Median Spaces

    Location: MSRI: Simons Auditorium
    Created on Sep 13, 2016 09:55 AM PDT
  3. Common Lunch

    Location: MSRI: Commons Room
    Created on Aug 25, 2016 01:46 PM PDT
  4. Graduate Student Seminar

    Location: MSRI: Baker Board Room
    Created on Aug 25, 2016 02:07 PM PDT
  5. Postdoc Seminar I

    Location: MSRI: Simons Auditorium
    Updated on Aug 26, 2016 09:23 AM PDT
  6. Postdoc Seminar II

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:30 AM PDT
  7. Member Seminar: Discontinuous Motions of limit sets

    Location: MSRI: Simons Auditorium
    Speakers: Mahan Mj (Tata Institute of Fundamental Research)

    It is well known, thanks to work of Mane-Sad-Sullivan  that for a parametrized family of quasifuchsian groups (or equivalently convex cocompact discrete surface subgroups of PSl(2,C)) the limit set moves holomorphically on the Riemann sphere. We shall discuss what happens when a sequence of such groups converges to a non-quasifuchsian group. A discontinuity phenomenon was discovered in joint work with Caroline Series. In further work with Ken'ichi Ohshika, we characterize when precisely these discontinuities arise.

    Updated on Sep 20, 2016 03:59 PM PDT
  8. Working Seminar: Median Spaces

    Location: MSRI: Simons Auditorium
    Created on Sep 13, 2016 09:56 AM PDT
  9. Common Lunch

    Location: MSRI: Commons Room
    Created on Aug 25, 2016 01:47 PM PDT
  10. Graduate Student Seminar

    Location: MSRI: Baker Board Room
    Created on Aug 25, 2016 02:07 PM PDT
  11. Postdoc Seminar I

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:24 AM PDT
  12. Postdoc Seminar II

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:31 AM PDT
  13. Member Seminar: Cannon-Thurston maps for hyperbolic free group extensions

    Location: MSRI: Simons Auditorium
    Speakers: Ilya Kapovich (University of Illinois at Urbana-Champaign)

    Let $F_N$ be a free group of finite rank $N\ge 3$ and let $\Gamma\le Out(F_N)$ be a finitely generated "convex cocompact" subgroup, that is, such that the orbit map from $\Gamma$ to the free factor complex of $F_N$ is a quasi-isometric embedding. Assume also that $\Gamma$ is purely atoroidal. In this case $\Gamma$ determines an extension group $E_\Gamma$ of $\Gamma$ with the quotient $E_\Gamma/F_N=\Gamma$, and it is known by a result of Dowdall and Taylor that the group $E_\Gamma$ is then word-hyperbolic. By a general result of Mitra the inclusion of $F_N$ in $E_\Gamma$ extends to a continuous surjective $F_N$-equivariant map between their hyperbolic boundaries $j: \partial F_N\to \partial E_\Gamma$, called the Cannon-Thurston map. We analyze the structure of this map and prove that the map is finite-to-one, with multiplicity at most $2N$. The talk is based on a joint paper with Spencer Dowdall and Sam Taylor. 

    Updated on Sep 20, 2016 03:53 PM PDT
  14. Working Seminar: Median Spaces

    Location: MSRI: Simons Auditorium
    Created on Sep 13, 2016 09:57 AM PDT
  15. Common Lunch

    Location: MSRI: Commons Room
    Created on Aug 25, 2016 01:48 PM PDT
  16. Graduate Student Seminar

    Location: MSRI: Baker Board Room
    Created on Aug 25, 2016 02:09 PM PDT
  17. Postdoc Seminar I

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:24 AM PDT
  18. Postdoc Seminar II

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:31 AM PDT
  19. Member Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 25, 2016 01:59 PM PDT
  20. Common Lunch

    Location: MSRI: Commons Room
    Created on Aug 25, 2016 01:49 PM PDT
  21. Math on YouTube

    Location: MSRI: Commons Room
    Created on Sep 13, 2016 09:50 AM PDT
  22. Graduate Student Seminar

    Location: MSRI: Baker Board Room
    Created on Aug 25, 2016 02:10 PM PDT
  23. Postdoc Seminar I

    Location: MSRI: Simons Auditorium
    Updated on Aug 26, 2016 09:25 AM PDT
  24. Postdoc Seminar II

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:32 AM PDT
  25. Member Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 25, 2016 01:59 PM PDT
  26. Common Lunch

    Location: MSRI: Commons Room
    Created on Aug 25, 2016 01:50 PM PDT
  27. Graduate Student Seminar

    Location: MSRI: Baker Board Room
    Created on Aug 25, 2016 02:11 PM PDT
  28. Postdoc Seminar I

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:26 AM PDT
  29. Postdoc Seminar II

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:32 AM PDT
  30. Member Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 25, 2016 02:00 PM PDT
  31. Common Lunch

    Location: MSRI: Commons Room
    Created on Aug 25, 2016 01:50 PM PDT
  32. Graduate Student Seminar

    Location: MSRI: Baker Board Room
    Updated on Sep 16, 2016 12:18 PM PDT
  33. Postdoc Seminar I

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:34 AM PDT
  34. Postdoc Seminar II

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:33 AM PDT
  35. Member Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 25, 2016 02:01 PM PDT
  36. Common Lunch

    Location: MSRI: Commons Room
    Created on Aug 25, 2016 01:52 PM PDT
  37. Member Seminar

    Location: MSRI: Simons Auditorium
    Created on Aug 25, 2016 02:01 PM PDT
  38. Common Lunch

    Location: MSRI: Commons Room
    Created on Aug 25, 2016 01:53 PM PDT
  39. Graduate Student Seminar

    Location: MSRI: Baker Board Room
    Created on Aug 25, 2016 02:12 PM PDT
  40. Postdoc Seminar I

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:26 AM PDT
  41. Postdoc Seminar II

    Location: MSRI: Simons Auditorium
    Created on Aug 26, 2016 09:34 AM PDT

Past Seminars

seminar
  1. Seminar Common Lunch

    Created on Aug 25, 2016 01:44 PM PDT
  2. Seminar Job Market Panel

    Created on Sep 16, 2016 11:22 AM PDT
  3. Seminar Common Lunch

    Created on Aug 25, 2016 01:41 PM PDT
  4. Seminar Graduate Student Seminar

    Created on Aug 25, 2016 02:02 PM PDT
There are more then 30 past seminars. Please go to Past seminars to see all past seminars.