# About

I am a 4th-year mathematics PhD candidate at the University of Oklahoma. I am working under the direction of Max Forester. I spend most of my time thinking about topics in the field of Geometric Group Theory. I organize the Student Geometry and Topology Seminar with Paul Plummer. See the section for more info.

I also work as a graduate teaching assistant in the math department. I am currently on the job market for a mathematics teaching position at a post-secondary institution. See the

section for more info.In addition to mathematics, my hobbies include card games (Hanabi and poker are my favorites), skateboarding, longboarding, rollerblading, jazz piano, and Super Smash Bros (64 and Melee). You can find some of my other interests in the

section.### Contact

- Office: PHSC 826
- Email: bwstucky AT ou DOT edu
- PGP key: public.txt

# Research

My graduate research lies in the field of Geometric Group Theory (GGT). This is a relatively new field, the origins of which trace back to Henri Poincaré, Max Dehn, and others. The current viewpoint is motivated by influential ideas of Mikhail Gromov and William Thurston, to name a few. Broadly, geometric group theorists seek to understand groups via their presentations by finding nice spaces which encode their symmetry. One then uses the geometry and topology of those spaces to derive algebraic properties of those groups.

I am interested specifically in generalizations of one-relator groups (ORGs). ORGs are groups which admit a presentation with one or more generators and a single defining relator. These groups bear some similarities to their prototypes -- free groups and surface groups, and one can ask how deep these similarities run. I am interested in conditions which ensure that ORG's have "negative curvature," meaning that they admit nice actions on spaces which resemble hyperbolic space (as do, e.g., closed surface groups) or infinite trees (as do, e.g., free groups). Curiously, groups which admit negative curvature enjoy many nice properties which make them much easier to study than general groups.

### Hadwiger-Nelson Problem

Around 1950, Ed Nelson asked the seemingly innocuous question, "What is the smallest number of colors needed to color the plane so that no two points distance one apart are the same color?" It was established quickly and straightforwardly that the answer, which we call the chromatic number of the plane, lies between 4 and 7, inclusive, but the exact answer has proved difficult to come by. See Wikipedia for a nice synopsis of this problem.

This is one of my favorite open problems, and I have written a program to explore how one might raise the lower bound. My approach is to immerse a graph of chromatic number 5 (meaning that one needs to use 5 colors to paint the vertices in such a way that no two adjacent vertices have the same color) in the plane, and then use a method called stochastic proximity embedding to treat the edges like springs which are length 1 when balanced. One picks a spring at random and moves it towards equilibrium by a small amount. After repeating this process several thousand times, we hope that we have made each spring close to length 1. This would be strong evidence that the chromatic number of the plane is actually greater than or equal to 5.

There are several challenges to overcome in order to get this approach to work. First, computing the chromatic number of a graph is a computationally hard problem, so getting lots of good graphs to start with is no simple task. Second, the graphs I did use do not seem to come close to having edges of length 1 after running them through the program, so one needs to find a clever way to "shake loose" or perturb a graph when it gets tangled. Third, simply knowing that all of the springs are close to being balanced does not mean that they are actually balanced, so we must find a way to decide that a graph which looks balanced actually is balanced.

- This graph shows that the chromatic number of the plane is at least 4.
- This tiling shows that the chromatic number of the plane is at most 7.
- An example of a graph I would feed to the program.
- What a graph might look like after being run through the program. The green edges are springs which are close to balanced.

### Visual Proofs

I love geometric proofs. One of my favorite things to do in my Calculus II class is to show my students a visual proof of the "sum of squares" formula \[\sum_{i=1}^ni^2=\frac{n(n+1)(2n+1)}{6},\] which comes up when computing Riemann integrals from the definition. The particular proof that I give was shown to me by a professor I knew during my time with Budapest Semesters in Mathematics. I challenged myself to come up with an analagous proof of the "sum of cubes" formula (sometimes called Nicomachus' Theorem), \[\sum_{i=1}^ni^3=\frac{n^2(n+1)^2}{4}.\] The result is the proof described in this write-up from 2015:

# Teaching

I have almost six years of teaching at the college level. The courses that I have taught include College Algebra, Precalculus and Trigonometry, Math for Critical Thinking (a basic introduction to statistics), Calculus I, and Calculus II. I have also TA'ed Calculus III and Calculus IV. In the summer of 2016 I taught a class called Paradoxes and Infinities to gifted 7th through 10th graders. This unique course introduced middle and high school students to topics not typically covered until college, including Peano Arithmetic and Cantor's Diagonalization, and it challenged me to implement classroom methodology with which I was not as familiar.

I am passionate about teaching and have reflected considerably about what I believe makes a successful teacher. See my teaching philosophy for more information.

### Evaluations

Most of my students seem to respond well to my approach in the classroom. Here are some select student evaluations.

- During the summer of 2017 I taught Calculus II to a class of 18 students. View their evaluations here.
- During the spring of 2017 I TA'ed an Honors Calculus II course for Dr. Ameya Pitale, leading a discussion section of 24 students. View their evaluations here.

# Links

### Math blogs

- Low Dimensional Topology Blog
- Here There Be Dragons
- Danny Calegari
- Wilton - Geometric Group Theory
- Chiasme
- Alessandro Sisto
- Baking & Math
- Sketches of Topology

### Math vlogs

- 3Blue1Brown
- Mathologer
- Numberphile (this one is pretty hit-or-miss)