My primary research area is algebraic topology. I like to apply stable homotopy theory (spectra) to questions about manifolds and cell complexes. My work has taken a recent turn towards scissors congruence: last year I proved that it is described by a Thom spectrum, and I am developing the consequences of this surprising result for the higher scissors congruence groups. I am partially supported by the grants NSF DMS-2005524 and NSF DMS-2052923.
Key words: algebraic topology, homotopy theory, spectra, G-spectra, parametrized spectra, free loop spaces, topological Hochschild homology (THH), algebraic K-theory, duality, traces, transfers, scissors congruence, Nielsen theory (fixed-point theory), h-cobordisms, high-dimensional manifolds.
- Spectra and stable homotopy theory.
(first 6 chapters, 344 pages)
-
Periodic-point structures on parametrized spectra: An application of rigidity.
(with Kate Ponto) -
A convenient category of parametrized spectra.
This replaces the earlier preprint "Parametrized spectra, a low-tech approach." (submitted) -
On the functoriality of the space of equivariant smooth h-cobordisms.
(with Thomas Goodwillie, Kiyoshi Igusa, and Mona Merling; submitted) -
A trace map on higher scissors congruence groups.
(with Anna Marie Bohmann, Teena Gerhardt, Mona Merling, and Inna Zakharevich; submitted) -
On the multiplicativity of the Euler characteristic.
(with John Klein and Maxime Ramzi; Proceedings of the American Mathematical Society 2023) -
Scissors congruence K-theory is a Thom spectrum.
(submitted) -
Coherence for bicategories, lax functors, and shadows.
(with Kate Ponto; Theory and Applications of Categories 2021) -
K-theoretic torsion and the zeta function.
(with John Klein; Annals of K-theory 2022) -
K-theory of endomorphisms, the TR-trace, and zeta functions.
(with Jonathan Campbell, John Lind, Kate Ponto, and Inna Zakharevich; submitted) -
The equivariant parametrized h-cobordism theorem, the non-manifold part.
(with Mona Merling; Advances in Mathematics 2022) -
Coassembly is a homotopy limit map.
(with Mona Merling; Annals of K-theory 2020) -
Periodic points and topological restriction homology.
(with Kate Ponto; International Mathematics Research Notices 2020) -
Comparing cyclotomic structures on different models for topological Hochschild homology.
(with Emanuele Dotto, Irakli Patchkoria, Steffen Sagave, and Calvin Woo; Journal of Topology 2019) -
The Morita equivalence between parametrized spectra and module spectra.
(with John Lind; Contemporary Mathematics 2018) - Equivariant A-theory.
(with Mona Merling; Documenta Mathematica 2019) - The transfer map of free loop spaces.
(with John Lind; Transactions of the AMS 2019) - Cyclotomic structure in the topological Hochschild homology of DX.
(Algebraic & Geometric Topology 2017) - The topological cyclic homology of the dual circle.
(Journal of Pure and Applied Algebra 2017) - Coassembly and the K-theory of finite groups. >>> See also the user's guide. <<<
(Advances in Mathematics 2017) - A tower connecting gauge groups to string topology.
(Journal of Topology 2015)
Other publications and preprints:
-
Parametrized spectra, a low-tech approach. >>> See also the user's guide. <<<
This has been condensed into the research article "A convenient category of parametrized spectra." -
Spectral Waldhausen categories, the S.-construction, and the Dennis trace.
(with Jonathan Campbell, John Lind, Kate Ponto, and Inna Zakharevich) -
Coherence for indexed symmetric monoidal categories.
(with Kate Ponto) - The transfer is functorial.
(with John Klein) This paper had a mistake, see here and here. - The user's guide project: giving experiential context to research papers.
(with Mona Merling, David White, Luke Wolcott, and Carolyn Yarnall; Journal of Humanistic Mathematics) - Duality and linear approximations in Hochschild homology, K-theory, and string topology.
(Ph.D. thesis) This comes with errata.
I am currently teaching MATH 330: Number Systems and MATH 601A: Stable homotopy and algebraic K-theory.
- The Reidemeister trace (free loop transfer) in pictures (JMM 2017)
- A visual introduction to cyclic sets and cyclotomic spectra (YTM 2015)
- Fundamental theorems for THH (2021)
- Parametrized spectra, a user's guide (2020)
- Bicategories, pseudofunctors, shadows: a cheat sheet (tables) (2018)
- Bicategories, pseudofunctors, shadows: a cheat sheet (text) (2018)
- A user's guide: Coassembly and the K-theory of finite groups (2015)
- The stable homotopy category (2012-2014)
- The Steenrod algebra (2012)
- The bar construction and BG (2011)
- Unoriented cobordism and MO (2011)
In preparation:
- Spectra and stable homotopy theory. (first 6 chapters, 344 pages)
- A user's guide to G-spectra. Draft version here.
For a curated list of expository writings by other authors, see this website.
- Comparing a cell complex to a colimit of subcomplexes (2023)
- Morita adjunctions and Morita duality (2017)
- The transfer on the n-fold cover of the circle (2014)
- Semistability, The Bokstedt smash product, and classical fibrant replacement for diagram spectra (2017)
- Finite spectra (2015)
- Pushouts in the homotopy category do not exist (2014)
- Fibration sequences and pullback squares (2014)
- Fixed points and colimits (2014)
- Homotopy colimits via the bar construction (2014)
- Finiteness, phantom maps, completion, and the Segal conjecture (2013)
- The gluing lemma is left-properness (2013)
- Some facts about QX (2011)
I am one of the organizers of Binghamton's Geometry and Topology Seminar. I am co-organizing a workshop on scissors congruence K-theory in the summer of 2023 and a collaborative workshop on the same subject in the summer of 2024. In the past I organized the Topology Seminar at UIUC and the Stanford student topology seminar, and was involved with the "xkcd" discussion group, and the String topology seminar.
I've learned a lot from my experience as a teacher, a parent, and a relationship partner. If you're interested in some of the insights that I picked up along the way, you can find them here.