Research

I’m a low-dimensional topologist with a special interest in dimension four. I’m particularly interested in the development and application of the theory of trisections of four-manifolds. The tools I use most often are trisections, Floer cohomology theories, and their sheaf-theoretic counterparts.

Teaching and mentoring

REU topology mentor

Summer 2021 (virtual)
University of Virginia

In the summer of 2021, I participated as a mentor for the topology REU hosted by UVA. My primary responsibilities were two-fold: I wrote an introductory minicourse on classical knot theory, and I supervised a group of six students (four undergraduate partipants and two graduate student mentors) through a research project which studied the Alexander invariants of knotted 2-spheres embedded in four-space.

MATH 8750 Topology of Manifolds

Fall 2021
University of Virginia

An introduction to smooth four-manifold topology with an eye towards the applicationss of trisections and the constructions of small exotic four-manifolds.

MATH 2310--Calculus III

Fall 2020, Spring 2021, Spring 2022, Fall 2022, Spring 2023
University of Virginia

A continuation of Calc I and II, this course is about functions of several variables. Topics include finding maxima and minima of functions of several variables/surfaces and curves in three-dimensional space/integration over these surfaces and curves. Additional topics: conservative vector fields/Stokes’ and the divergence theorem/how these concepts relate to real world applications. Prerequisite: MATH 1320 or the equivalent.

Experiences

Postdoctoral researcher at the Center for Quantum Mathematics at Syddansk Universitet

Fall 2023 - Present
University of Southern Denmark

Supervised by Vivek Shende

RTG Postdoctoral researcher and lecturer at the University of Virginia

Fall 2020 - Spring 2023
University of Virginia

Supervised by Thomas E. Mark

Graduate student at the University of Georgia

2014 - 2020
UGA, Athens Georgia

While a graduate student at UGA, I also enjoyed spending the academic year 2019-2020 in the guest program at the Max Planck Institute for Mathematics in Bonn, Germany.

Publications and preprints

My work is centers on developing the theory of trisections of four-manifolds, as introduced by Gay and Kirby. So far, this has meant applying techniques of modern symplectic geometry in the form of Heegaard Floer and quilted Floer cohomology to this geometric situation.

Given a smooth four-manifold with connected boundary and equipped with a trisected Morse 2-function we demonstrate how to compute the relative invariant of Ozsvath and Szabo in the setting of Heegaard Floer homology.

Honghao Gao and William E. Olsen

One can associate to any codimension two embedding its unit conormal lift. Here, we study the microlocal sheaf category of Kashiwara and Schapira associated to tangles and knotted surfaces in four-space, and we prove a homotopy limit formula which computes these categories using a local-to-global approach.

Ethan Clelland, Calvin Godfrey, Alexandra Emmons, Lusa Grisales, and William E. Olsen

Cimansoni and Conway have constructed an Alexander-Burau 2-functor which takes values in a 2-cospan category of modules over a Laurent polynomial ring. We apply their construction in the setting of bridge-trisected 2-knots. Our main result realizes the Alexander module of a 2-knot as a categorical trace in the sense of Kapranov.

On Lasagna operads

In preparation
Ross Ackmechet, Julie Bergner, William E. Olsen, Walker Stern

We show that the Lasagna fillings of Morrison-Walker-Wedrich constitute a homotopy operad in the form of a dendroidal space. See, for example:

Equity in Mathematics

I do my best to incorporate research-based teaching practices in support of equity and diversity within mathematics. Listed below are a few links which I’ve found useful and enlightening:

Seminar Invitations

A list of my invited seminar talks. Most recently, I’ve focused on discussing my work with Honghao Gao on applying microlocal sheaf theory to bridge-trisected surface knots.

University of Georgia

William E. Olsen

We adapt Seidel’s construction from Lefschetz fibrations to broken Lefschetz fibrations which relates Heegaard Floer homology to Perutz’s Lagrangian matching invariants.