All of my research involves number theory of various flavors. I am very interested in how sub-rings of quaternion algebras over number fields can be used to construct groups, manifolds, and sphere packings. I also have interest in additive number theory and logic.

## Papers:

- The Ulam Sequence of the Integer Polynomial Ring. arXiv: 1910.00109
- Algebraic Groups Constructed from Orders of Quaternion Algebras. arXiv:1908.01250
- Quaternion Orders and Sphere Packings. Journal of Number Theory, 204 (2019) 41-98.
- Rigidity of Ulam Sets and Sequences (co-authored with J. Hinman, B. Kuca, and A. Schlesinger). Involve, 12(3) (2019) 521-539.
- The Unreasonable Rigidity of Ulam Sequences (co-authored with J. Hinman, B. Kuca, and A. Schlesinger). Journal of Number Theory 194 (2019) 409-425.
- Orders of Quaternion Algebras with Involution. Journal of Number Theory, 183 (2018) 249-268.
- A Corrigendum to Unreasonable Slightness. The American Mathematical Monthly, 123(5) (2016) 482-85.

## Talks:

- Graduate Center.
*The Quaternion-Bianchi Dictionary.*Nov. 2019. - Illustrating Number Theory and Algebra (at ICERM).
*Euclidean Algorithm in Circle/Sphere Packings*. Oct. 2019. Slides available here. Video recording available here. - Journées sur les Arithmétiques Faibles (at CUNY).
*Applications of Model Theory to Families of Integer Sequences*. May. 2019 - Graduate Center.
*Hyperbolic Isometry Groups and Quaternion Algebras.*Apr. 2019. - Graduate Center.
*(Searching for)**Applications of Orders with Involution.*Mar. 2019. Slides available here. - Bronx Community College.
*Two Trivial Problems and an Impossible One*. Dec. 2018. Slides available here. - Integers 2018.
*Rigidity in the Ulam Sequence*. Oct. 2018. Slides available here. - New York Logic Model Seminar at CUNY.
*Rigidity in the Ulam Sequence.*Sep. 2018. - CANT at CUNY.
*Rigidity in the Ulam Sequence*. May 2018. - Rutgers University.
*Connections between Integral Sphere Packings and Quaternion Algebras.*May 2018. Slides available here. - Dartmouth College.
*Quaternion Algebras and Integral Sphere Packings*. Feb. 2017. - University of Colorado, Boulder.
*Quaternion Algebras and Integral Sphere Packings*. Oct. 2016.

## REU Students:

- 2017 SUMRY (
*The Unreasonable Rigidity of Ulam Sets)*:- Joshua Hinman
- Borys Kuca
- Alexander Schlesinger

- 2016 SUMRY (
*Embeddings of Imaginary Quadratic Fields into Rational Quaternion Algebras*):- Alexander Schlesinger
- Rose Mintzer-Sweeney
- Katherine Xiu

- 2015 DIMACS REU (
*Cymatics-Chlandi plates*):- Lolly Kenigsberg