# Topology, Algebraic Geometry, and Dynamics Seminar (TADS)

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## Topology, Algebraic Geometry, and Dynamics Seminar (TADS)

TADS is a venue for presentation/discussion concerning topology, algebraic geometry, or dynamics (broadly understood).

Attendance is open, and those interested in giving a talk should e-mail title/abstract to David Carchedi (dcarched at gmu.edu).

**Unless noted otherwise, talks will be on Fridays from 1:30pm - 2:30pm.**

**In-person: Exploratory Hall, room 4208**

## Spring 2024

**January 26**

Combinations of parabolically geometrically finite groups

Brian Udall, Rice University

## Past Seminars

### Fall 2023

**September 15**

Understanding equivariant elliptic cohomology for non-abelian Lie groups

David Gepner, Johns Hopkins University

**September 29**

Geometric and algebraic reduction of multisymplectic manifolds

Casey Blacker, George Mason University

**October 13**

Riemannian foliations and geometric

quantization

Yiannis Loizides, George Mason University

**November 10**

Higher scissors congruence invariants for manifolds

Mona Merling, University of Pennsylvania

**November 17**

The Rarita-Schwinger Operator, from Index Theory to Gauge Theory

Ahmad R.H.S. Sadegh, Northeastern University

### Spring 2023

**February 10**

Solenoids are more interesting than you previously thought

Rodrigo Trevino, UMD

**March 24**

Geodesic flow on CAT(-1) spaces

Dave Constantine, Wesleyan University

**March 31**

Discontinuities of the Integrated Density of States for Penrose Laplacians

May Mei, Denison University

**April 14**

String topology, integrable systems, and noncommutative geometry

Nick Rozenblyum, University of Chicago

**April 21**

Abstract posted soon

David Gepner, Johns Hopkins

### Fall 2022

**September 23**

Moduli of flat connections on surfaces and the Atiyah-Bott classes

Yiannis Loizides, GMU

**September 30**

Quantum Field Theory and Derived Differential Geometry (Part I)

David Carchedi, GMU

**October 7**

Quantum Field Theory and Derived Differential Geometry (Part II)

David Carchedi, GMU

**October 14**

Frobenius algebras and symplectic categories

Walker Stern, UVA

**October 28**

Mixed Hodge Structures on Character Varieties of Nilpotent Groups

Sean Lawton, GMU

**November 4 - Meeting in Exploratory Hall, room 4106**

Sara Maloni, UVA

**November 11**

A global measure formula and logarithm law for convex real projective structures

Harry Bray, GMU

**December 2**

Topological Field Theory and Homological Algebra

Chris Elliot, UMass

### Spring 2022

**March 11 - Special Time: 3:30pm-4:30pm**

Dynamics on nilpotent character varieties

Sean Lawton, George Mason University

**April 1**

Supermanifolds and derived differential geometry

David Carchedi, George Mason University

**April 8**

Convergence of higher-dimensional continued fractions: Part 2

Anton Lukyanenko, George Mason University

**April 15**

Plaquette Percolation on the Torus

Benjamin Schweinhart, George Mason University

**May 13**

Virtual classes of character stacks

Marton Hablicsek, Leiden University

### Fall 2020

**Friday, December 4, 2020**

Chern-Simons theory on cylinders and generalized Hamilton-Jacobi actions

Pavel Mnev, Notre Dame

**Friday, November 20, 2020**

The higher characteristic polynomial

Cary Malkiewich, Binghamton University

**November 13, 2020**

Holomorphic SCFTs of small index

Theo Johnson-Freyd, Dalhousie University & Perimeter Institute

### Spring 2020

**February 28, 2020**

A gentle approach to crystalline cohomology

Akhil Mathew, University of Chicago

**February 21, 2020**

Factorization algebras in topology and physics

Owen Gwilliam, UMass Amhrest

**February 7, 2020**

Closed affine manifolds with partially hyperbolic linear holonomy

Suhyoung Choi, KAIST

### Fall 2019

**December 6, 2019**

Discretely shrinking targets in moduli space

Grace Work, Girls' Angle and M.I.T.

**November 22, 2019**

The Peterson Isomorphism: Moduli of Curves and Alcove Walks

Elizabeth Milicevic, Haverford College

**November 15, 2019**

An introduction to generalized splines

Julianna Tymoczko, Smith College

**November 1, 2019**

Strings of beads and the equivariant cohomology or Peterson varieties

Brent Gorbutt, George Mason University

**October 18, 2019**

K-theory stable basis of Springer resolutions

Changlong Zhong, SUNY Albany

**October 4, 2019**

Positivity determines quantum cohomology

Anders Buch, Rutgers University

**September 20, 2019**

Cotangent Schubert Calculus

Leonardo Mihalcea, Virginia Tech

**September 6, 2019**

Algebraic Groups with Good Reduction

Groups with good reduction slides

Andrei Rapinchuk, University of Virginia

### Spring 2019

**April 26, 2019**

Polygon Spaces

Jack Love, George Mason University

**April 19, 2019**

Special nilpotents and Higher Teichmüller spaces

Brian Collier, University of Maryland, College Park

**April 5, 2019**

Expanding Thurston maps and visual spheres

Annina Iseli, University of California, Los Angeles

**March 22, 2019**

Capturing invariance in flows and combinatorial vector fields

Tom Wanner, George Mason University

**March 8, 2019**

Singularities of commutative rings via test ideals

Rebecca Rebhuhn-Glanz, George Mason University

**February 22, 2019**

Dynamics and the Clebsch diagonal cubic surface

William Goldman, University of Maryland, College Park

**February 8, 2019**

How self-driving robots find delivery paths, and how this leads to sub-Riemannian geometry

Anton Lukyanenko, George Mason University

**January 25, 2019**

Explicit modular forms via the homotopy groups of spheres.

Donald Larson, Catholic University of America

### Fall 2018

**November 30, 2018**

Convex hulls of quasicircles in hyperbolic and anti-de Sitter space

Sara Maloni, University of Virginia

**November 16, 2018**

Battle Hymn of Discreteness

Caleb Ashley, University of Michigan

**November 2, 2018**

On some (equivariant) combinatorics related to flag manifolds

Rebecca Goldin, GMU

**October 26, 2018**

Quasi-isometries of the Baumslag-Gersten group

Tullia Dymarz, University of Wisconsin–Madison

**September 28, 2018**

Toric Vector Bundles and Piecewise Linear Maps

Christopher Manon, University of Kentucky

**September 14, 2018**

Ergodicity of Iwasawa continued fractions via markable hyperbolic geodesics

Anton Lukyanenko, GMU

### Spring 2018

**April 27, 2018** Morse theory and a stack of broken lines

Hiro Lee Tanaka, Harvard University

**April 6, 2018** Topological realization of varieties over Spec C((t)) via log geometry

Mattia Talpo, Simon Fraser University

**April 6, 2018** Connecting Outreach and Continued Fraction Expansions Through Tessellations

Claire Merriman, UIUC**Special Time:** 4:40-5:30pm

**March 30, 2018** Representation stability, homological stability, and commuting matrices

Daniel Ramras, Indiana University–Purdue University Indianapolis

**March 2, 2018** Hilbert Schemes and the Motivic Sphere Spectrum

Elden Elmanto, Northwestern University

**February 23, 2018** Homotopy types of moduli spaces of foliations

David Carchedi, GMU

**February 16, 2018** Some results on affine Deligne-Lusztig varieties

Xuhua He, UMCP

**February 9, 2018** How to do Multivariable Calculus on Graphs

Tyrus Berry, GMU

**January 23, 2018** Poisson Structure on Compactification of Moduli Space of Representations

Sean Lawton, GMU

### Fall 2017

**November 17, 2017** Lipschitz maps from PI spaces to Carnot groups

Kyle Kinneberg

**October 20, 2017** Dirichlet domains in different geometries

Todd Drumm, Howard University

**October 13, 2017 **Homotopy types as a foundation for mathematics

Emily Riehl, JHU

**October 6, 2017** Counting matrices with forced zero entries

Joel Lewis, George Washington University

**September 22, 2017** An invitation to the Heisenberg group and its deformations

Anton Lukyanenko, GMU

**September 15, 2017** Free products and regularity of group actions

Thomas Koberda, UVA

**September 8, 2017** Can rotation numbers be computed from a quasiperiodic trajectory?

Evelyn Sander, GMU

### Spring 2017

**May 5, 2017** Hyperbolic localization and nearby cycles

Tom Haines, UMCP

**April 14, 2017** The Erdos-Szekeres Problem

Valeriu Soltan, GMU

**April 7, 2017** Quotient of surface groups and homology of finite covers via Topological Quantum Field Theories

Ramanujan Santharoubane, University of Virginia

**March 24, 2017** Invertible Orbifolds over Finite Fields

Marco Aldi, Virginia Commonwealth University

**March 10, 2017** Accessing Geometry via Function Spaces

Tyrus Berry, GMU

**March 3, 2017** Manifolds, Schemes, Deligne-Mumford stacks, and Orbifolds: Why they’re all topoi.

David Carchedi, GMU

**February 17, 2017** Tropical geometry of complexity 1 T -varieties

Chris Manon, GMU

**February 10, 2017** Families of Unitary Representations and Kazhdan’s Property (T)

Dan Ramras, IUPUI

**February 3, 2017** Compactification of Character Varieties

Sean Lawton, GMU

**January 27, 2017** An introduction to 2−Segal spaces

Julie Bergner, UVA

### Fall 2016

**December 15, 2016** Tropicalization of Configurations of Flags

Ian Le, Perimeter Institute for Theoretical Physics**Special Date/Location:** 12/15/16, Fishbowl (4th floor of Exploratory Hall)

**December 9, 2016** Operads with homological stability

Sarah Yeakel, University of Maryland

**December 2, 2016** SO(p, q)-surface group representations

Brian Collier, University of Maryland

**October 28, 2016** Parabolic Higgs Bundles & Generalized Parabolic Higgs Bundles

Marina Logares, Oxford

**October 21, 2016** Polyhedra inscribed in quadrics and their geometry

Sara Maloni, University of Virginia

**October 14, 2016** Schottky groups and maximal representations

Jean-Philippe Burelle, University of Maryland

**September 30, 2016** How to make 3-D printed sculptures of 4-D things. (Public Lecture)

Henry Segerman, Oklahoma State University**Special Location and Time:** The HUB Ballroom, 2-3pm presention, 3-4pm book-signing.

**September 16, 2016 **Introduction to hyperrings and hyperfields

Jaiung Jun, Binghamton University

### Spring 2016

**May 20, 2016** Positivity in Schubert Calculus, Part 2

Rebecca Goldin, George Mason University

**May 13, 2016** Rank 1 Character Varieties

Sean Lawton, George Mason University

**April 29, 2016** Positivity in Schubert Calculus

Rebecca Goldin, George Mason University

**April 15, 2016** Geometry of the Vinberg’s Enveloping Monoid

Chris Manon, George Mason University

**March 21, 2016** Voronoi Tilings and Loop Groups

Pablo Solis , CalTech

**March 18, 2016** Algebraic Vision: the Quadrifocal Variety

Luke Oeding, Auburn University

**March 4, 2016** The Gauss map and Diophantine approximation in the Heisenberg group

Anton Lukyanenko, University of Michigan

**February 19, 2016** Genus of complete intersections in spherical varieties

Kiumars Kaveh, University of Pittsburgh

**February 5, 2016** Strange duality of non-abelian theta functions

Swarnava Mukhopadhyay, University of Maryland, College Park

### Fall 2015

**December 18, 2015** Higgs bundles at the Fuchsian locus

Richard Wentworth, University of Maryland, College Park

**December 4, 2015** Algebraic Properties of Skein Algebras of Surfaces

Adam Sikora, State University of New York at Buffalo

**November 13, 2015** Stable Representation Theory and Spaces of Flat Connections

Daniel Ramras, Indiana University-Purdue University Indianapolis

**November 6, 2015** A new approach to etale homotopy theory

David Carchedi, GMU

**October 30, 2015** Geometry and Connectivity of Space of Finite Unit-Norm Tight Frames

Nate Strawn, Georgetown

**October 9, 2015** Coordinates for representations of 3-manifold groups

Christian Zickert, University of Maryland, College Park

**September 25, 2015** How to pinch a neck on a convex RP2 surface.

John Loftin, Rutgers-Newark

### Summer 2015

**July 24, 2015 **Tropical computational experiments with compactifications of the deformation spaces of convex real projective structures on 2-orbifolds and surfaces

Suhyoung Choi, Korean Advanced Institute of Science and Technology (KAIST)

### Spring 2015

**April 24, 2015** The space of local overrings of an integral domain

Neil Epstein, George Mason University

**April 10, 2015** Equations of tropical varieties

Jeffrey Giansiracusa, Swansea University

**March 6, 2015** Proper affine deformations of the one-holed torus

Todd Drumm, Howard University

**February 27, 2015** Zeta functions and motivic measures

Niranjan Ramachandran, University of Maryland

**February 13, 2015** Complex dynamics and elliptic curves

Laura DeMarco, Northwestern University

**January 30, 2015** Representation theory of symplectic singularities

Ben Webster, University of Virginia

### Fall 2014

**December 3, 2014** Primitive Geodesic Lengths and Arithmetic Progressions

Ben McReynolds, Purdue University

Special Time: 5-6pm

**November 19, 2014** Tameness of Margulis Spacetimes

William Goldman, University of Maryland

**November 12, 2014** Homotopy of Character Varieties

Sean Lawton, George Mason University

**October 29, 2014** The geometry of Euclidean polygons

Chris Manon, George Mason University

**October 15, 2014** Counting Points on a Moduli Space

Sean Lawton, George Mason University