Nicholas Ramsey

I am an Assistant Professor of Mathematics at the University of Notre Dame. My research is in model theory, in the sense of mathematical logic, and its interactions with algebra and combinatorics.

I received my PhD in Logic and the Methodology of Science from UC Berkeley in 2018 and was a postdoc at UCLA and at ENS before joining Notre Dame. My work explores Kim-independence, NSOP₁ theories, pseudofinite structures, and the model theory of fields, groups, and measures.

My CV (PDF) and Google Scholar. You can reach me at sramsey5@nd.edu.

Work

(I'm happy to share any writing you don't already have access to. Just ask!)

Selected Papers

• "Measures on bounded perfect PAC fields" (with Zoé Chatzidakis), submitted, arxiv.
• "Primitive pseudo-finite permutation groups of finite SU-rank" (with Ulla Karhumäki), Transactions of the American Mathematical Society, to appear, arxiv.
• "A two-sorted theory of nilpotent Lie algebras" (with Christian d'Elbée, Isabel Müller, and Daoud Siniora), Journal of Symbolic Logic, to appear, arxiv.
• "Some model theory of quadratic geometries" (with Charlotte Kestner), submitted, arxiv.
• "NSOP₁ as a Dividing Line," Logic and Its Applications (ICLA 2025), Lecture Notes in Computer Science, vol. 15402, Springer, 2025, doi.
• "Model-theoretic properties of nilpotent groups and Lie algebras" (with Christian d'Elbée, Isabel Müller, and Daoud Siniora), Journal of Algebra 662, 640-701, 2025, doi, arxiv.
• "A New Kim's Lemma" (with Alex Kruckman), Model Theory 3 (3), 825-860, 2024, doi, arxiv.
• "Generic Stability Independence and Treeless Theories" (with Itay Kaplan and Pierre Simon), Forum of Mathematics, Sigma 12, e49, 2024, doi, arxiv.
• "Measures on perfect e-free PAC fields" (with Zoé Chatzidakis), Israel Journal of Mathematics 257 (1), 171-191, 2023, doi, arxiv.
• "Invariant measures in simple and in small theories" (with Artem Chernikov, Ehud Hrushovski, Alex Kruckman, Krzysztof Krupinski, Slavko Moconja, and Anand Pillay), Journal of Mathematical Logic 23 (2), 2023, doi, arxiv.
• "Exact saturation in pseudo-elementary classes for simple and stable theories" (with Itay Kaplan and Saharon Shelah), Journal of Mathematical Logic 23 (2), 2023, doi, arxiv.
• "Transitivity, lowness, and ranks in NSOP₁ theories" (with Artem Chernikov and Byunghan Kim), Journal of Symbolic Logic 88 (3), 919-946, 2023, doi, arxiv.
• "Criteria for exact saturation and singular compactness" (with Itay Kaplan and Saharon Shelah), Annals of Pure and Applied Logic 172 (9), 2021, doi, arxiv.
• "Independence over arbitrary sets in NSOP₁ theories" (with Jan Dobrowolski and Byunghan Kim), Annals of Pure and Applied Logic 173 (2), 2022, doi, arxiv.
• "Transitivity of Kim-independence" (with Itay Kaplan), Advances in Mathematics 379, 2021, doi, arxiv.
• "A note on NSOP₁ in one variable," Journal of Symbolic Logic 84 (1), 388-392, 2019, doi, arxiv.
• "Local character of Kim-independence" (with Itay Kaplan and Saharon Shelah), Proceedings of the American Mathematical Society 147 (4), 1719-1732, 2017, doi, arxiv.
• "Generic expansion and Skolemization in NSOP₁ theories" (with Alex Kruckman), Annals of Pure and Applied Logic 169 (8), 755-774, 2018, doi, arxiv.
• "On Kim-Independence" (with Itay Kaplan), Journal of the European Mathematical Society 22 (5), 1423-1474, 2020, doi, arxiv.
• "Invariants related to the tree property," Israel Journal of Mathematics 240, 275-314, 2020, doi, arxiv.
• "On model-theoretic tree properties" (with Artem Chernikov), Journal of Mathematical Logic 16 (2), 2016, doi, arxiv.

Dissertation

Independence, Amalgamation, and Trees, UC Berkeley, Group in Logic and the Methodology of Science, 2018, pdf.

Teaching

I am currently teaching Beginning Logic (MATH 10130) at Notre Dame.

In 2020, I taught a graduate course on model-theoretic tree properties. The video lectures are available online.

Selected Talks

• "Model-theoretic Tree Properties," Workshop on Neostability Theory, Casa Matemática Oaxaca, July 13, 2015, video.
• "Classification Theory and the Construction of PAC fields," Workshop on Neostability Theory, Casa Matemática Oaxaca, October 18, 2018, video.
• "Groups and Measures in Simple Theories," MSRI Model Theory Seminar, November 19, 2020, video.
• "Mini-course: An Introduction to Kim-independence and NSOP₁ Theories," Fudan University, Shanghai, October-November 2020, course page.
• "Binarity, Treelessness, and Generic Stability," Model Theory and Applications, Cetraro, June 2022, slides.
• "The Mathematics of Truth," Young Scholars Program, Chicago, July 2022, slides.