Seminar Calendar
for Geometry, Groups and Dynamics/GEAR events the next 12 months of Sunday, January 1, 2017.

     .
events for the
events containing  

(Requires a password.)
More information on this calendar program is available.
Questions regarding events or the calendar should be directed to Tori Corkery.
    December 2016           January 2017          February 2017    
 Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa
              1  2  3    1  2  3  4  5  6  7             1  2  3  4
  4  5  6  7  8  9 10    8  9 10 11 12 13 14    5  6  7  8  9 10 11
 11 12 13 14 15 16 17   15 16 17 18 19 20 21   12 13 14 15 16 17 18
 18 19 20 21 22 23 24   22 23 24 25 26 27 28   19 20 21 22 23 24 25
 25 26 27 28 29 30 31   29 30 31               26 27 28            
                                                                   

Thursday, January 19, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Thursday, January 19, 2017
 Del 
 Edit 
 Copy 
Submitted by nmd.
Xinghua Gao   [email] (University of Illinois)
Orders from $\widetilde{PSL_2(\mathbb{R})}$ Representations and Non-examples.
Abstract: Let $M$ be an integer homology 3-sphere. One way to study left-orderability of $\pi_1(M)$ is to construct a non-trivial representation from $\pi_1(M)$ to $\widetilde{PSL_2(\mathbb{R})}$. However this method does not always work. In this talk, I will give examples of non L-space irreducible integer homology 3-spheres whose fundamental groups do not have nontrivial $\widetilde{PSL_2(\mathbb{R})}$ representations.

Tuesday, January 24, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Tuesday, January 24, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Sarah Mousley (Illinois Math)
Boundary maps for some hierarchically hyperbolic spaces
Abstract: There are natural embeddings of right-angled Artin groups $G$ into the mapping class group $Mod(S)$ of a surface $S$. The groups $G$ and $Mod(S)$ can each be equipped with a geometric structure called a hierarchically hyperbolic space (HHS) structure, and there is a notion of a boundary for such spaces. In this talk, we will explore the following question: does an embedding $\phi: G \rightarrow Mod(S)$ extend continuously to a boundary map $\partial G \rightarrow \partial Mod(S)$? That is, given two sequences $(g_n)$ and $(h_n)$ in $G$ that limit to the same point in $\partial G$, do $(\phi(g_n))$ and $(\phi(h_n))$ limit to the same point in $\partial Mod(S)$? No background in HHS structures is needed.

Thursday, February 2, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Thursday, February 2, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Nick Vlamis (U Michigan Math)
Algebraic and topological properties of big mapping class groups
Abstract: There has been a recent surge in studying surfaces of infinite type, i.e. surfaces with infinitely-generated fundamental groups. In this talk, we will focus on their mapping class groups, often called big mapping class groups. In contrast to the finite-type case, there are many open questions regarding the basic algebraic and topological properties of big mapping class groups. I will discuss several such questions and provide some answers. In particular, I will focus on automorphisms of pure mapping class groups and topological generating sets. This work is joint with Priyam Patel.

Tuesday, February 7, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Tuesday, February 7, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Gili Golan (Vanderbilt)
The generation problem in Thompson group F
Abstract: We show that the generation problem in Thompson group F is decidable, i.e., there is an algorithm which decides if a finite set of elements of F generates the whole F. The algorithm makes use of the Stallings 2-core of subgroups of F, which can be defined in an analogue way to the Stallings core of subgroups of a free group. An application of the algorithm shows that F is a cyclic extension of a group K which has a maximal elementary amenable subgroup B. The group B is a copy of a subgroup of F constructed by Brin and Navas.

Tuesday, February 21, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Tuesday, February 21, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
John P. D'Angelo (Illinois Math)
Groups Associated with Rational Proper Maps
Abstract: Given a rational proper map $f$ between balls of typically different dimensions, we define a subgroup $\Gamma_f$ of the source automorphism group. We prove that this group is noncompact if and only if $f$ is linear. We show how these groups behave under certain constructions such as juxtaposition and partial tensor products. We then sketch a proof of the following result. If $G$ is an arbitrary finite subgroup of the source automorphism group, then there is a rational map $f$ for which $\Gamma_f = G$. We provide many examples and, if time permits, discuss the degree estimate conjecture. This work is joint with Ming Xiao.

Tuesday, February 28, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Tuesday, February 28, 2017
 Del 
 Edit 
 Copy 
Submitted by nmd.
Malik Obeidin   [email] (University of Illinois)
Hyperbolic volumes of random links
Abstract: What does a random link look like? There have been a few different proposed models for sampling from the set of links -- in this talk, I will describe a model based on random link diagrams in the plane. Such diagrams can be sampled uniformly on a computer due to the work of Gilles Schaeffer, so one can experiment with various invariants of links with the topology software SnapPy. I will present data showing what happens with some of the different invariants SnapPy can compute, and I will outline a proof that the hyperbolic volume of the complement of a random alternating link diagram is asymptotically a linear function of the number of crossings. In contrast, for nonalternating links, I will show why the diagrams we get generically represent satellite (and hence nonhyperbolic) links.

Thursday, March 9, 2017

Geometry, Groups and Dynamics/GEAR
12:00 pm   in 243 Altgeld Hall,  Thursday, March 9, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Mark Bell (Illinois Math)
To Be Announced

Tuesday, March 14, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Tuesday, March 14, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Mark Sapir (Vanderbilt and Illinois Math)
Flat submaps in CAT(0) $(p,q)$-maps and maps with angles
Abstract: This is a joint work with A. Olshanskii. Let $p, q$ be positive integers with $1/p+1/q=1/2$. We prove that if a $(p,q)$-map $M$ does not contain flat submaps of radius $\ge r$, then its area does not exceed $c(r+1)n$ where $n$ is the perimeter of $M$ and $c$ is an absolute constant. Earlier Ivanov and Schupp proved an exponential bound in terms of $r$. We prove an estimate similar to Ivanov and Schupp for much more general ``maps with angles" which include, for example, van Kampen diagrams over the presentation of the Baumslag-Solitar group $BS(1,2)$ and many groups corresponding to $S$-machines. We also show that a $(p,q)$ map $M$ tessellating a plane ${\mathbb R}^2$ has path metric quasi-isometric to the Euclidean metric on the plane if and only if $M$ has only finitely many non-flat vertices and faces.

Tuesday, March 28, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Tuesday, March 28, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Charles Delman (EIU Math)
To Be Announced

Thursday, April 6, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Thursday, April 6, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Autumn Kent (Wisconsin Math)
To Be Announced

Thursday, April 13, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Thursday, April 13, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Catherine Pfaff (UC Santa Barbara)
To Be Announced

Tuesday, April 18, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Tuesday, April 18, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Edgar Bering (UIC Math)
To Be Announced

Tuesday, April 25, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Tuesday, April 25, 2017
 Del 
 Edit 
 Copy 
Submitted by clein.
Funda Gultepe (Illinois Math)
To Be Announced