Michael Chapman's Homepage
Short Bio
I am currently a Simons Junior Fellow based at Courant Institute, NYU, under the mentorship of Professors Subhash Khot and Oded Regev.
Previously I was a PhD student at the Einstein institute of Mathematics, The Hebrew University, under the supervision of Professors Alex Lubotzky and Nati Linial
HUJI Mail: michael.chapman@mail.huji.ac.il
Academic Interests
Group Theory, Graph Theory, High Dimensional Combinatorics, Quantum Information Theory, Complexity Theory
Publications and Preprints
L. Bowen, M. Chapman, T. Vidick, The Aldous--Lyons Conjecture II: Undecidability , preprint (2024) [arXiv] [PDF]
M. Chapman, Y. Dikstein, A. Lubotzky, Conditional Non-Soficity of p-adic Deligne Extensions: on a Theorem of Gohla and Thom, preprint (2024) [arXiv]
L. Bowen, M. Chapman, A. Lubotzky, T. Vidick, The Aldous--Lyons Conjecture I: Subgroup Tests, preprint (2024) [arXiv] --- See Section 6 of [Gol24] for a beautiful summary of our work.
M. Chapman, I. Dinur, A. Lubotzky, Non-commutative error correcting codes and proper subgroup testing, preprint (2024) [arXiv]
M. Chapman, A. Lubotzky, Stability of Homomorphisms, Coverings and Cocycles II: Examples, Applications and Open problems, Advances in mathematics (accepted) (2023) [arXiv]
M. Chapman, T. Vidick, H. Yuen, Efficiently stable presentations from error-correcting codes, preprint (2023) [arXiv]
M. Chapman, A. Lubotzky, Stability of Homomorphisms, Coverings and Cocycles I: Equivalence, European Journal of Mathematics (accepted) (2023) [arXiv]
D. Aharonov, M. Chapman, On proofs, entanglement and games, a technical perspective for the Communications of the ACM, volume 64, issue 11 (Nov 2021).
O. Becker, M. Chapman, Stability of approximate group actions: uniform and probabilistic, Journal of the European Mathematical Society (2020) [arXiv]
M. Chapman, O. Parzanchevski, Cutoff on Ramanujan Complexes and Classical groups, Commentarii Mathematici Helvetici 97 (2022), no. 3, pp. 431–456 [arXiv] [PDF]
M. Chapman, N. Linial and Y. Peled, Expander graphs -- Both local and global, Combinatorica 40 (2020) , pp. 473–509 [arXiv] [PDF]. A shortened version appears in the proceedings of FOCS 2019.
A. Chapman and M. Chapman, Symbol p-Algebras of prime degree and their p-central subspaces, Archiv der Mathematik 108 (2017), Issue 3, pp. 241–249 [arXiv] [PDF]
M. Chapman and I. Efrat, Filtrations of free groups arising from the lower central series, J. Group Theory 19 (2016), special issue in memory of O. Melnikov, pp 405--433. [arXiv] [PDF]
Selected Talks
Subgroup tests and the Aldous--Lyons conjecture:
Berkeley TCS lunch seminar and probability seminar, 2.10.2024.
IAS CSDM seminar, 7-8.10.2024. Recordings: First talk, Second talk.
NYU colloquium, 28.10.2024.
Columbia's combined math and computer science seminar, 1.11.2024.
Oxford GGT seminar, 12.11.2024.
Cambridge GGT seminar, 13.11.2024.
Winter school on expansion in groups, combinatorics, and complexity - Weizman institute 5-8.1.25. [Lec1] [Lec2] [Lec3]
University of Waterloo colloquium, 17.1.2025.
Analytic Group Theory mini-school, UT Austin, 17-21.3.2025.
Groups and Geometry School, Renyi Institute Budapest, 31.3-4.4.2025
Current Developments in Mathematics 2025, Harvard and MIT, 4-5.4.2025
Property testing in group theory:
Midrasha - Weizman institute 31.8.23, Special Seminar - HUJI 30.8.23 ,Combinatorics seminar - Dartmouth college 6.6.23, TCS seminar - Columbia 21.4.23.
The call for efficient stability:
Entropic methods for cutoff:
Amitsur seminar (YouTube, Notes) 27.1.22, MPS conference on high dimensional expanders 27-29.10.21, IMU annual meeting -- Ergodic theory and groups session 6.7.21.
Stability of approximate group actions:
TCS seminar, NYU 8.12.22, Fields institute SDV seminar, Toronto (via ZOOM) 2.11.22, Zuchovitzky prize lecture at the HUJI math colloquium 10.6.21 [Notes], Combinatorics seminar (ZOOM) at Bar Ilan 21.3.21, TCS seminar at BGU 2.12.19, Algebra seminar at Haifa university 9.12.19, TCS seminar at HUJI 17.6.20 [Slides] (Oren's talk 27.5.20: ETH Online geometry seminar, Slides)
Cutoff on Ramanujan Complexes and Classical groups [Notes]:
Combinatorics seminar Bar Ilan university, 10.3.19. Horowitz seminar Tel-Aviv university, 25.3.19. Groups & Dynamics seminar, HUJI, 27.6.19. ETH online geometry seminar, 7.4.20.
Graphs which are expanders both locally and globally [Notes]:
Combinatorics Seminar HUJI, 12.11.18. Weizmann institute, 13.12.18. Combinatorics Seminar Technion, 10.4.19. Combinatorics Seminar TAU, 5.5.19. Combinatorial Theory seminar Oxford, 14.5.19. Short version at Student Combinatorics Day, BIU, 7.7.19. HDX Summer cluster, Simons institute Berkeley, 23.8.19. FOCS2019, 10.11.19, Presentation in memory of Ela Lipcer (Video).
Filtrations of free groups and Magnus' theory, Algebra seminar, Western University, Canada, May 2016 [Notes]
More talks and talk notes appear in the teachings section.
Oct 16--20, 2023
Tips for students
Tips for Exam Preperation (Hebrew)
Tips for Exam Writing (Hebrew)
Tips for writing a good answer (Hebrew)
Additional Activities
I was the chief instructor & academic advisor of Israel's Junior Science Team between Jan 2018 and Dec 2020.
Before that, between Oct 2011 and Aug 2018, I was part of the academic staff of Israel's Junior Mathematics Team and occasionally assisted the academic staff of Israel's IMO team.