Talk_id  Date  Speaker  Title 
13345

Thursday 9/6 2:00 PM

Alex Waldron, MSU

YangMills flow in dimension four
 Alex Waldron, MSU
 YangMills flow in dimension four
 09/06/2018
 2:00 PM  3:00 PM
 C304 Wells Hall
Among the classical geometric evolution equations, YM flow is the least nonlinear and best behaved. Nevertheless, curvature concentration is a subtle problem when the base manifold has dimension four. I'll discuss my proof that finitetime singularities do not occur, and briefly describe the infinitetime picture.

13292

Thursday 9/13 2:00 PM

Rita Gitik, Michigan

On Tame Subgroups of Finitely Presented Groups
 Rita Gitik, Michigan
 On Tame Subgroups of Finitely Presented Groups
 09/13/2018
 2:00 PM  2:50 PM
 C304 Wells Hall
We describe several examples of tame subgroups of finitely presented groups and prove that the fundamental groups of certain finite graphs of groups are locally tame.

15396

Thursday 9/27 2:00 PM

Giuseppe Martone, University of Michigan

Hitchin representations and positive configurations of apartments
 Giuseppe Martone, University of Michigan
 Hitchin representations and positive configurations of apartments
 09/27/2018
 2:00 PM  3:00 PM
 C304 Wells Hall
Hitchin singled out a preferred component in the character variety of representations from the fundamental group of a surface to PSL(d,R). When d=2, this Hitchin component coincides with the Teichm\"uller space consisting of all hyperbolic metrics on the surface. Later Labourie showed that Hitchin representations share many important differential geometric and dynamical properties.
Parreau extended previous work of Thurston and MorganShalen to a compactification of the Hitchin component whose boundary points are described by actions of the fundamental group of the surface on a building.
In this talk, we offer a new point of view for the Parreau compactification, which is based on certain positivity properties discovered by Fock and Goncharov. Specifically, we use the FockGoncharov construction to describe the intersection patterns of apartments in invariant subsets of the building that arises in the boundary of the Hitchin component.

14370

Thursday 10/4 2:00 PM

Artem Kotelskiy, Indiana University

Khovanov homology and BarNatan's deformation via immersed curves in the 4punctured sphere.
 Artem Kotelskiy, Indiana University
 Khovanov homology and BarNatan's deformation via immersed curves in the 4punctured sphere.
 10/04/2018
 2:00 PM  2:50 PM
 C304 Wells Hall
We will describe a geometric interpretation of Khovanov homology and its deformation due to BarNatan as Lagrangian Floer homology of two immersed curves in the 4punctured 2sphere S^2 \ 4pt. We will first start with a certain cobordism theoretic algebra H, where elements are all cobordisms between two trivial tangles )( and = up to certain relations. The central point then will be the observation that this algebra is isomorphic to an algebra B = Fuk(a0, a1), whose elements are generators of wrapped Lagrangian Floer complexes between two arcs a0 and a1 inside S^2 \ 4pt. The results will follow because D structures over H give Khovanov/BarNatan invariants for 4ended tangles, and D structures over B give curves in S^2 \ 4pt (due to [Haiden, Katzarkov, Kontsevich]).
The construction is originally inspired by a result of [Hedden, Herald, Hogancamp, Kirk], which embeds 4ended reduced Khovanov arc algebra (or, equivalently, BarNatan dotted cobordism algebra) into the Fukaya category of the 4punctured sphere. This is joint work with Liam Watson and Claudius Zibrowius.

15379

Thursday 10/11 2:00 PM

Matthew Stoffregen, MIT

An infiniterank summand of the homology cobordism group
 Matthew Stoffregen, MIT
 An infiniterank summand of the homology cobordism group
 10/11/2018
 2:00 PM  3:00 PM
 C304 Wells Hall
This talk explains a generalization of the techniques that Hom introduced to construct an infiniterank summand of the topologically slice knot concordance group. We generalize Hom's epsiloninvariant to the involutive Heegaard Floer homology constructed by HendricksManolescu. As an application, we see that there is an infiniterank summand of the homology cobordism group, generated by Seifert spaces. The talk will contain a review of involutive Floer homology. This is joint work with Irving Dai, Jen Hom, and Linh Truong.

15434

Thursday 10/18 2:00 PM

Siddhi Krishna, Boston College

Taut Foliations, Positive 3Braids, and the LSpace Conjecture
 Siddhi Krishna, Boston College
 Taut Foliations, Positive 3Braids, and the LSpace Conjecture
 10/18/2018
 2:00 PM  3:00 PM
 C304 Wells Hall
The LSpace Conjecture is taking the lowdimensional topology community by storm. It aims to relate seemingly distinct Floer homological, algebraic, and geometric properties of a closed 3manifold Y. In particular, it predicts a 3manifold Y isn't "simple" from the perspective of HeegaardFloer homology if and only if Y admits a taut foliation. The reverse implication was proved by Ozsvath and Szabo. In this talk, we'll present a new theorem supporting the forward implication. Namely, we'll use branched surfaces to build taut foliations for manifolds obtained by surgery on positive 3braid closures. As an example, we'll construct taut foliations in every nonLspace obtained by surgery along the P(2,3,7) pretzel knot. No background in HeegaardFloer or foliation theories will be assumed.

16445

Thursday 10/18 3:10 PM

Min Hoon Kim, KIAS

Freely slice good boundary links
 Min Hoon Kim, KIAS
 Freely slice good boundary links
 10/18/2018
 3:10 PM  4:00 PM
 C304 Wells Hall
No abstract available.

15386

Thursday 10/25 2:00 PM

William Worden, Rice University

TBA
 William Worden, Rice University
 TBA
 10/25/2018
 2:00 PM  3:00 PM
 C304 Wells Hall
No abstract available.

15387

Thursday 11/1 2:00 PM

Yuanqi Wang

TBA
 Yuanqi Wang
 TBA
 11/01/2018
 2:00 PM  3:00 PM
 C304 Wells Hall
No abstract available.

13346

Thursday 11/8 2:00 PM

Jonathan Campbell, Vanderbilt University

TBA
 Jonathan Campbell, Vanderbilt University
 TBA
 11/08/2018
 2:00 PM  3:00 PM
 C304 Wells Hall
No abstract available.

14374

Thursday 11/15 2:00 PM

Ian Zemke, Princeton University

TBA
 Ian Zemke, Princeton University
 TBA
 11/15/2018
 2:00 PM  3:00 PM
 C304 Wells Hall
No abstract available.

15380

Thursday 11/29 2:00 PM

Dominic Culver, University of Illinois UrbanaChampaign

TBA
 Dominic Culver, University of Illinois UrbanaChampaign
 TBA
 11/29/2018
 2:00 PM  3:00 PM
 C304 Wells Hall
No abstract available.

15397

Thursday 12/6 2:00 PM

Lev TovstopyatNelip , Boston College

TBA
 Lev TovstopyatNelip , Boston College
 TBA
 12/06/2018
 2:00 PM  2:50 PM
 C304 Wells Hall
No abstract available.
