# Mathematical Sciences Research Institute

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1. # Geometry and Analysis of Surface Group Representations: Introduction to Spectral Networks (II)

Location: MSRI: Baker Board Room
Speakers: Daniele Alessandrini (Ruprecht-Karls-Universität Heidelberg)

I will give an introduction to the theory of Spectral Networks, developed by Gaiotto, Moore and Neitzke during their research about supersymmetry.

These objects have an independent interest for mathematicians, mostly in the theory of surfaces. They can be described as combinatorical objects on the surface, or, equivalently as some orbits associated to a conformal structure on the surface and a collection of holomorphic differentials.

The main focus will be on how to use these objects to give coordinates on the moduli spaces of representations of surface groups. These coordinates generalise Fenchel-Nielsen coordinates and Fock-Goncharov coordinates in an especially intriguing way.

Updated on Mar 26, 2015 04:16 PM PDT
2. # Lorentzian geometric structures seminar: Margulis spacetimes and contracting deformations of hyperbolic surfaces II

Location: MSRI: Baker Board Room
Speakers: Jeffrey Danciger (University of Texas)

This second talk will go into more details of the proof.

We will describe a properness criterion for free groups acting by isometries of Minkowski 3-space in terms of the deformation theory of hyperbolic surfaces. A corollary of the criterion is that every Margulis spacetime fibers in lines over a hyperbolic surface.

We will discuss some details of the proof, including the case in which the linear part has parabolics. This talk is based on joint work with François Guéritaud and Fanny Kassel.

Updated on Mar 26, 2015 03:39 PM PDT
1. # DMS Research Seminar: Renormalized volume, Weil-Petersson geometry and volumes of hyperbolic 3-manifolds that fiber over the circle

Location: MSRI: Simons Auditorium
Speakers: Jeffrey Brock (Brown University), Kenneth Bromberg (University of Utah)

The notion of "renormalized volume" gives a way to assign a finite volume to an infinite volume hyperbolic 3-manifold. Krasnov and Schlenker showed (following a similar result for Schottky space by Takhtjan-Teo) that the renormalized volume on a Bers slice gives a potential for the Weil-Petersson metric on Teichmüller space - Schlenker, in turn, used this idea to give an effective version of bounds due to Brock on the volume of the convex core of quasifuchsian manifolds in terms the Weil-Petersson distance between the two components of the conformal boundary. Kojima-McShane connected Schlenker's idea to volumes of hyperbolic 3-manifolds that fiber of the circle and the normalized entropy on pseudo-Anosov mapping class (Teichmüller translation length). We discuss a proof of improved bounds (originally due to Brock) in terms of the Weil-Petersson translation length to volumes of mapping tori as well as new implications for the length spectrum and systolic geometry of moduli space with the Weil-Petersson metric.  We will give an elementary overview and introduction to the above, with a particular emphasis on new results on the geometry of the Weil-Petersson metric.

Updated on Mar 27, 2015 03:36 PM PDT
2. # DMS Postdoc Seminar: Coupled Hitchin Equations

Location: MSRI: Simons Auditorium
Speakers: Qiongling Li (Rice University)

In this talk, I will talk about a technical part in the joint paper with Brian Collier about studying asymptotic behavior of Hitchin representations in terms of Higgs bundles. This technical part estimates the asymptotic solution of the coupled Hitchin equations. I will also discuss how the analysis is related to geometry of frames.

Updated on Mar 26, 2015 04:14 PM PDT
3. # GAAHD Postdoc Seminar: The stable type of the mapping class group and some relatively hyperbolic groups and applications to pointwise ergodic averages

Location: MSRI: Simons Auditorium
Speakers: Ilya Gekhtman (Yale University)

The stable ratio set of a nonsingular action is a notion introduced by Bowen and Nevo to prove pointwise ergodic theorems for measure preserving actions of certain nonamenable groups.

I  prove that stable ratio set of the action of a discrete subgroup of isometries of a CAT(-1) space with finite Bowen-Margulis measure on its boundary with the Patterson-Sullivan measure has numbers other than 0, 1 and \infinity, extending techniques of Bowen from the setting of hyperbolic groups.

I also prove the same result for the action of the mapping class group on the sphere of projective measured foliations with the Thurston measure, using some "statistical hyperbolicity" properties for the (non hyperbolic) Teichmueller metric on Teichmueller space.

Updated on Mar 26, 2015 03:44 PM PDT
4. # Lorentzian geometric structures seminar

Location: MSRI: Baker Board Room
Created on Feb 23, 2015 11:02 AM PST
5. # MSRI Evans Talk: Dynamics on moduli spaces of flat surfaces - questions and new directions

Location: 60 Evans Hall
Speakers: Maryam Mirzakhani (Stanford University)
In this talk, we will discuss various basic problems regarding the topology, geometry and dynamical systems on surfaces: all these questions are closely related to the study of closed Riemann surfaces endowed with a holomorphic one-form. This is the same as having a flat metric on the surface with finitely many cone-type singularities.

The moduli space of holomorphic one-forms on a closed surface of genus $g$ has a natural piecewise linear structure and carries an action of GL(2,R).
One can investigate the geometry and dynamics of an individual flat surface by studying its orbit under this linear group action.

One famous example is how understanding a billiard path on a rational billiard is related to studying the orbits of the action of GL(2,R) on the moduli spaces of flat surfaces.

Many of the results in this area are motivated by statements in homogenous dynamics. On the other hand, they have strong connections with other topics in algebraic geometry and number theory. In this talk, I will give an overview of some known results and open questions regarding these moduli spaces.
Updated on Mar 30, 2015 12:00 PM PDT
6. # GAAHD Research Seminar

Location: MSRI: Simons Auditorium
Updated on Feb 20, 2015 09:47 AM PST
7. # 3-Manifold Seminar

Location: 939 Evans Hall
Speakers: Ian Agol (University of California, Berkeley)
The topic this semester is representations of 3-manifold groups into SL_2 C. Topics will include:

- character varieties and curves of characters
- ideal points, R-tree actions, tree actions associated to ideal points of curves
- associating incompressible surfaces to tree actions and measured laminations to R-tree actions
- volumes of representations and Chern-Simons invariant
- Dehn invariants, the Bloch group, and extensions
- volume rigidity, via simplicial volume and the barycenter map
- the A-polynomial

Created on Jan 29, 2015 09:26 AM PST
8. # Open ended seminar

Location: MSRI: Baker Board Room
Updated on Mar 06, 2015 09:52 AM PST
9. # Geometry and Analysis of Surface Group Representations

Location: MSRI: Baker Board Room
Speakers: Qiongling Li (Rice University), Andrew Sanders (University of Illinois at Chicago)
Created on Jan 22, 2015 04:35 PM PST
10. # DMS Research Seminar

Location: MSRI: Simons Auditorium
Speakers: Marc Burger (Eidgenössische TH Zürich-Hönggerberg), Fanny Kassel (Université de Lille I (Sciences et Techniques de Lille Flandres Artois))
Updated on Jan 28, 2015 02:17 PM PST
11. # DMS Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Guillaume Dreyer (University of Notre Dame), Nicolas de Saxce (Université de Paris XIII (Paris-Nord))
Created on Jan 28, 2015 01:54 PM PST
12. # GAAHD Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Guillaume Dreyer (University of Notre Dame), Nicolas de Saxce (Université de Paris XIII (Paris-Nord))
Created on Jan 28, 2015 01:55 PM PST
13. # Lorentzian geometric structures seminar

Location: MSRI: Baker Board Room
Created on Feb 23, 2015 11:04 AM PST
14. # GAAHD Research Seminar

Location: MSRI: Simons Auditorium
Updated on Feb 20, 2015 09:49 AM PST
15. # 3-Manifold Seminar

Location: 939 Evans Hall
Speakers: Ian Agol (University of California, Berkeley)
The topic this semester is representations of 3-manifold groups into SL_2 C. Topics will include:

- character varieties and curves of characters
- ideal points, R-tree actions, tree actions associated to ideal points of curves
- associating incompressible surfaces to tree actions and measured laminations to R-tree actions
- volumes of representations and Chern-Simons invariant
- Dehn invariants, the Bloch group, and extensions
- volume rigidity, via simplicial volume and the barycenter map
- the A-polynomial

Created on Jan 29, 2015 09:28 AM PST
16. # Open ended seminar

Location: MSRI: Baker Board Room
Updated on Mar 06, 2015 09:52 AM PST
17. # Geometry and Analysis of Surface Group Representations

Location: MSRI: Baker Board Room
Speakers: Qiongling Li (Rice University), Andrew Sanders (University of Illinois at Chicago)
Created on Jan 22, 2015 04:36 PM PST
18. # DMS Research Seminar

Location: MSRI: Simons Auditorium
Speakers: Marc Burger (Eidgenössische TH Zürich-Hönggerberg), Fanny Kassel (Université de Lille I (Sciences et Techniques de Lille Flandres Artois))
Updated on Jan 28, 2015 02:16 PM PST
19. # DMS Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Guillaume Dreyer (University of Notre Dame), Nicolas de Saxce (Université de Paris XIII (Paris-Nord))
Created on Jan 28, 2015 01:57 PM PST
20. # GAAHD Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Guillaume Dreyer (University of Notre Dame), Nicolas de Saxce (Université de Paris XIII (Paris-Nord))
Created on Jan 28, 2015 02:02 PM PST
21. # Lorentzian geometric structures seminar

Location: MSRI: Baker Board Room
Created on Feb 23, 2015 11:06 AM PST
22. # MSRI Evans Talk

Location: 60 Evans Hall
Speakers: Hee Oh (Yale University)
Updated on Jan 15, 2015 09:42 AM PST
23. # GAAHD Research Seminar

Location: MSRI: Simons Auditorium
Updated on Feb 20, 2015 09:49 AM PST
24. # 3-Manifold Seminar

Location: 939 Evans Hall
Speakers: Ian Agol (University of California, Berkeley)
The topic this semester is representations of 3-manifold groups into SL_2 C. Topics will include:

- character varieties and curves of characters
- ideal points, R-tree actions, tree actions associated to ideal points of curves
- associating incompressible surfaces to tree actions and measured laminations to R-tree actions
- volumes of representations and Chern-Simons invariant
- Dehn invariants, the Bloch group, and extensions
- volume rigidity, via simplicial volume and the barycenter map
- the A-polynomial

Created on Jan 29, 2015 09:29 AM PST
25. # Open ended seminar

Location: MSRI: Baker Board Room
Updated on Mar 06, 2015 09:51 AM PST
26. # Geometry and Analysis of Surface Group Representations

Location: MSRI: Baker Board Room
Speakers: Qiongling Li (Rice University), Andrew Sanders (University of Illinois at Chicago)
Created on Jan 22, 2015 04:38 PM PST
27. # DMS Research Seminar

Location: MSRI: Simons Auditorium
Speakers: Marc Burger (Eidgenössische TH Zürich-Hönggerberg), Fanny Kassel (Université de Lille I (Sciences et Techniques de Lille Flandres Artois))
Updated on Jan 28, 2015 02:15 PM PST
28. # DMS Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Guillaume Dreyer (University of Notre Dame), Nicolas de Saxce (Université de Paris XIII (Paris-Nord))
Created on Jan 28, 2015 02:04 PM PST
29. # GAAHD Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Guillaume Dreyer (University of Notre Dame), Nicolas de Saxce (Université de Paris XIII (Paris-Nord))
Created on Jan 28, 2015 02:05 PM PST
30. # Lorentzian geometric structures seminar

Location: MSRI: Baker Board Room
Created on Feb 23, 2015 11:07 AM PST
31. # GAAHD Research Seminar

Location: MSRI: Simons Auditorium
Updated on Feb 20, 2015 09:50 AM PST
32. # Open ended seminar

Location: MSRI: Baker Board Room
Updated on Mar 06, 2015 09:51 AM PST
33. # Geometry and Analysis of Surface Group Representations

Location: MSRI: Baker Board Room
Speakers: Qiongling Li (Rice University), Andrew Sanders (University of Illinois at Chicago)
Created on Jan 22, 2015 04:39 PM PST
34. # DMS Research Seminar

Location: MSRI: Simons Auditorium
Speakers: Marc Burger (Eidgenössische TH Zürich-Hönggerberg), Fanny Kassel (Université de Lille I (Sciences et Techniques de Lille Flandres Artois))
Updated on Jan 28, 2015 02:15 PM PST
35. # DMS Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Guillaume Dreyer (University of Notre Dame), Nicolas de Saxce (Université de Paris XIII (Paris-Nord))
Created on Jan 28, 2015 02:06 PM PST
36. # GAAHD Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Guillaume Dreyer (University of Notre Dame), Nicolas de Saxce (Université de Paris XIII (Paris-Nord))
Created on Jan 28, 2015 02:07 PM PST
37. # Lorentzian geometric structures seminar

Location: MSRI: Baker Board Room
Created on Feb 23, 2015 11:08 AM PST
38. # GAAHD Research Seminar

Location: MSRI: Simons Auditorium
Updated on Feb 20, 2015 09:52 AM PST
39. # Open ended seminar

Location: MSRI: Baker Board Room
Updated on Mar 06, 2015 09:50 AM PST
40. # Geometry and Analysis of Surface Group Representations

Location: MSRI: Baker Board Room
Speakers: Qiongling Li (Rice University), Andrew Sanders (University of Illinois at Chicago)
Created on Jan 22, 2015 04:40 PM PST
41. # DMS Research Seminar

Location: MSRI: Simons Auditorium
Speakers: Marc Burger (Eidgenössische TH Zürich-Hönggerberg), Fanny Kassel (Université de Lille I (Sciences et Techniques de Lille Flandres Artois))
Updated on Jan 28, 2015 02:14 PM PST

seminar
1. # Seminar3-Manifold Seminar

Created on Jan 29, 2015 09:25 AM PST
2. # SeminarOpen ended seminar: Quantum ergodicity on large graphs

Updated on Mar 26, 2015 03:48 PM PDT
3. # SeminarGAAHD Research Seminar: Density of lattice orbits on homogeneous varieties

Updated on Mar 26, 2015 03:46 PM PDT
4. # SeminarGAAHD Postdoc Seminar: Gap distributions for saddle connections on the octagon

Created on Mar 20, 2015 12:00 PM PDT
5. # SeminarDMS Postdoc Seminar: Andreev's theorem on projective Coxeter polyhedra

Created on Mar 20, 2015 11:57 AM PDT
6. # SeminarMinicourse

Created on Mar 23, 2015 09:57 AM PDT
7. # SeminarDMS Research Seminar: Stable commutator length on mapping class groups

Updated on Mar 20, 2015 11:42 AM PDT
8. # SeminarGeometry and Analysis of Surface Group Representations: Introduction to Spectral Networks

Updated on Mar 20, 2015 11:38 AM PDT
9. # SeminarOpen ended seminar: From dynamics to flat geometry

Updated on Mar 20, 2015 11:48 AM PDT
10. # SeminarGAAHD Research Seminar: Patterson-Sullivan Theory and Orbit Counting for Subgroups of Mapping Class Groups

Updated on Mar 20, 2015 11:47 AM PDT
11. # SeminarLorentzian geometric structures seminar: Margulis spacetimes and contracting deformations of hyperbolic surfaces

Updated on Mar 20, 2015 11:44 AM PDT
12. # SeminarSimplicial volume, barycenter method, and bounded cohomology

Created on Mar 16, 2015 09:03 AM PDT
13. # SeminarMinicourse

Created on Feb 23, 2015 10:43 AM PST
14. # SeminarGeometry and Analysis of Surface Group Representations: Hitchin representations and equivariant minimal surfaces

Updated on Mar 17, 2015 12:08 PM PDT
15. # Seminar3-Manifold Seminar

Created on Jan 29, 2015 09:23 AM PST
16. # SeminarOpen ended seminar: Orbits of diagonal flows

Updated on Mar 12, 2015 11:02 AM PDT
17. # SeminarGAAHD Research Seminar: Critical exponents, regular covers and amenability

Updated on Mar 13, 2015 10:02 AM PDT
18. # SeminarDMS Research Seminar: Affine deformations of one-holed torus

Updated on Mar 11, 2015 11:03 AM PDT
19. # SeminarGAAHD Postdoc Seminar: Sparse equidistribution under a unipotent flow

Created on Mar 05, 2015 04:18 PM PST
20. # SeminarDMS Postdoc Seminar: Degeneration of complex projective structures on surfaces that converges in the character variety

Created on Mar 05, 2015 04:20 PM PST
21. # SeminarMinicourse

Created on Feb 23, 2015 10:40 AM PST
22. # SeminarDMS Research Seminar: Counting, Randomness, and Renormalization

Updated on Feb 27, 2015 12:04 PM PST
23. # SeminarOpen ended seminar: Recurrence in random walks

Updated on Mar 05, 2015 04:24 PM PST
24. # Seminar3-Manifold Seminar

Created on Jan 29, 2015 09:22 AM PST
25. # SeminarGAAHD Research Seminar: Equidistribution of expanding translates of curves on homogeneous spaces

Updated on Mar 05, 2015 04:22 PM PST
26. # SeminarWomen in Science

Updated on Feb 05, 2015 12:10 PM PST
27. # SeminarMinicourse

Updated on Feb 23, 2015 10:37 AM PST
28. # SeminarDMS Research Seminar: Flows on irreducible parabolic geometries

Updated on Feb 27, 2015 12:13 PM PST
29. # SeminarGeometry and Analysis of Surface Group Representations: Cubic Differentials and Limits of Convex $RP^2$ Strucures under Neck Pinches

Updated on Feb 27, 2015 03:35 PM PST
30. # Seminar3-Manifold Seminar

Created on Jan 29, 2015 09:21 AM PST
There are more then 30 past seminars. Please go to Past seminars to see all past seminars.