Sean Moss

I am an Assistant Professor at the School of Computer Science, University of Birmingham.

I am co-organizing MGS 2027.

I am looking for PhD students. Please get in touch if you are interested in working with me.

Research

My mathematical and computer science interests include:

• Category theory: categorical probability theory, topos theory, categorical logic, fibred categories.
• Dependent type theory and its semantics, homotopy theory.
• Programming language theory: computational effects, probabilistic programming, local state, full abstraction.

I have been an Assistant Professor in Birmingham since August 2023. Before that I was a Senior Research Associate at the Department of Computer Science, University of Oxford, working with Sam Staton. From October 2017 to September 2021 I was a Junior Research Fellow at University College, Oxford. Previously I was a PhD student of Martin Hyland at the University of Cambridge.

I have worked with Philipp Koralus at the Faculty of Philosophy, Oxford, on a content-based theory of human cognitive capacity for reasoning and decision-making. One idea is to make precise the hypothesis that resolving questions is central to how the mind works. Part of this work was as a part-time Senior Researcher at HAI Lab in the academic year 2024–2025. Outputs include contributions to the book Reason and Inquiry and the PyETR package.

Publications and preprints

• Theory-Grounded Evaluation of Human-Like Fallacy Patterns in LLM Reasoning. Andrew Keenan Richardson, Ryan Othniel Kearns, Sean Moss, Vincent Wang-Mascianica, Philipp Koralus. ICLR 2026. OpenReview, Poster, Preprint: arXiv:2506.11128
• Scoped Effects, Scoped Operations, and Parameterized Algebraic Theories. Cristina Matache, Sam Lindley, Sean Moss, Sam Staton, Nicolas Wu, Zhixuan Yang. ACM Transactions on Programming Languages and Systems, Volume 47, Issue 2, 2025. doi:10.1145/3731678.
• Scoped Effects as Parameterized Algebraic Theories. Sam Lindley, Cristina Matache, Sean Moss, Sam Staton, Nicolas Wu, Zhixuan Yang. ESOP 2024. doi:10.1007/978-3-031-57262-3_1 Preprint: arXiv:2402.03103.
• Probabilistic Programming Interfaces for Random Graphs: Markov Categories, Graphons, and Nominal Sets. Nate Ackerman, Cameron E. Freer, Younesse Kaddar, Jacek Karwowski, Sean Moss, Daniel Roy, Sam Staton, Hongseok Yang. POPL 2024. doi:10.1145/3632903 Preprint: arXiv:2312.17127.
• Denotational semantics of languages for inference: semirings, monads, and tensors. Cristina Matache, Sean Moss, Sam Staton, Ariadne Si Suo. Accepted talk at LAFI 2023. Abstract: arXiv:2312.16694.
• A category-theoretic proof of the ergodic decomposition theorem. S. Moss, and P. Perrone. Ergodic Theory and Dynamical Systems, 2023. doi:10.1017/etds.2023.6 Preprint: arXiv:2207.07353.
• Probability monads with submonads of deterministic states. S. Moss, and P. Perrone. Proceedings of the 37th Annual ACM/IEEE Symposium on Logic in Computer Science (LICS 2022). doi:10.1145/3531130.3533355 Preprint: arXiv:2204.07003.
• Concrete categories and higher-order recursion (with applications including probability, differentiability, and full abstraction). C. Matache, S. Moss, and S. Staton. Proceedings of the 37th Annual ACM/IEEE Symposium on Logic in Computer Science (LICS 2022). doi:10.1145/3531130.3533370 Preprint: arXiv:2205.15917.
• Recursion and Sequentiality in Categories of Sheaves. C. Matache, S. Moss, and S. Staton. Proceedings of 6th International Conference on Formal Structures for Computation and Deduction (FSCD 2021). doi:10.4230/LIPIcs.FSCD.2021.25. Preprint: arXiv:2105.02156.
• Another approach to the Kan–Quillen model structure. S. Moss. Journal of Homotopy and Related Structures, vol 15, 2020. doi:10.1007/s40062-019-00247-y. Preprint: arXiv:1506.04887.
• Denotational validation of higher-order Bayesian inference. A. Ścibior, O. Kammar, M. Vákár, S. Staton, H. Yang, Y. Cai, K. Ostermann, S.K. Moss, C. Heunen, and Z. Ghahramani. Proceedings of 45th ACM SIGPLAN Symposium on Principles of Programming Languages (POPL 2018). doi:10.1145/3158148. Preprint: arXiv:1711.03219.
• Dialectica models of type theory. S.K. Moss and T. von Glehn. Proceedings of the 33rd Annual ACM/IEEE Symposium on Logic in Computer Science (LICS 2018). doi:10.1145/3209108.3209207. Preprint: arXiv:2105.00283.
• A monad for full ground reference cells. O. Kammar, P.B. Levy, S.K. Moss, and S. Staton. Proceedings of 32nd Annual ACM/IEEE Symposium on Logic in Computer Science (LICS 2017). doi:10.1109/LICS.2017.8005109. Preprint: arXiv:1702.04908.
• PhD thesis: The Dialectica Models of Type Theory. University of Cambridge. doi:10.17863/CAM.28036.