Igor Balla

Contact Info

E-mail address:	iballa1990gmail.com
Office address:	Ross 82, Einstein Institute of Mathematics
	Hebrew University, Givat Ram, Jerusalem 91904, Israel.
	Phone: +1 646 266 7919

I am a postdoctoral researcher at the Einstein Institute of Mathematics of the Hebrew University of Jerusalem, hosted by Eran Nevo and Alex Samorodnitsky. I completed my PhD in mathematics at ETH Zürich under the guidance of Benny Sudakov. Previously, I received a masters degree from New York University and a bachelors degree from Carnegie Mellon University.

I am broadly interested in combinatorics and its connections to linear algebra. My current focus is on certain extremal problems lying at the intersection of these areas. Apart from being beautiful and interesting in their own right, these problems have connections to probability, geometry, applied mathematics, theoretical computer science, and quantum physics. Check out my research featured in Quanta magazine - A New Path to Equal-Angle Lines

Curriculum Vitae: CV

Papers

Orthonormal representations, vector chromatic number, and extension complexity. Balla, I. (2023).
arXiv:2310.17482. Submitted.
Equiangular lines via matrix projection. Balla, I. (2021).
arXiv:2110.15842. Submitted.

Small Codes. Balla, I. (2023).
Bulletin of the London Mathematical Society, to appear.
On MaxCut and the Lovász theta function. Balla, I., Janzer, O., & Sudakov, B. (2023).
Proceedings of the American Mathematical Society, to appear.

Orthonormal representations of H-free graphs. Balla, I., Letzter, S., & Sudakov, B. (2020).
Discrete & Computational Geometry, 64 (3), 654-670.
The Minrank of Random Graphs over Arbitrary Fields. Alon, N., Balla, I., Gishboliner, L., Mond, A., & Mousset, F. (2018).
Israel Journal of Mathematics, 235 (1), 63-77.
Equiangular subspaces in Euclidean spaces. Balla, I., & Sudakov, B. (2018).
Discrete & Computational Geometry, 61 (1), 81-90.
Ramsey goodness of bounded degree trees. Balla, I., Pokrovskiy, A., & Sudakov, B. (2018).
Combinatorics, Probability and Computing, 27 (3), 289-309.
Equiangular Lines and Spherical Codes in Euclidean Space. Balla, I., Dräxler, F., Keevash, P., & Sudakov, B. (2018).
Inventiones Mathematicae, 211 (1), 179-212.
A remark on Hamilton cycles with few colors. Balla, I., Pokrovskiy, A., & Sudakov, B. (2017).
Moscow J. Combinatorics and Number Theory, 7 (3), 259-263.
Union-closed families of sets. Balla, I., Bollobás, B., & Eccles, T. (2013).
Journal of Combinatorial Theory Series A, 120 (3), 531-544.

Note on the second eigenvalue of regular graphs. Balla, I., Räty, E., Sudakov, B., & Tomon, I. (2023).
arXiv:2311.07629.
Minimum density of union-closed families. Balla, I. (2011).
arXiv:1106.0369.

Teaching

Spring 2019 - teaching assistant for Graph Theory, ETH Zurich.
Fall 2018 - teaching assistant for Algebra I, ETH Zurich.
Spring 2017 - teaching assistant for Graph Theory, ETH Zurich.
Spring 2016 - teaching assistant for Seminar on Elementary Number Theory, ETH Zurich.
Spring 2012 - teaching assistant for Matrix Theory, Carnegie Mellon University.
Spring 2010 - teaching assistant for Graph Theory, Carnegie Mellon University.

Talks

Dec 2023 - Equiangular lines via matrix projection, Discrete Mathematics Seminar, Princeton University.
Dec 2023 - Equiangular lines via matrix projection, Richard P. Stanley Seminar in Combinatorics, MIT/Harvard.
June 2023 - Equiangular lines via matrix projection, Combinatorics Seminar, Technion.
May 2023 - Equiangular lines via matrix projection, Combinatorics Seminar, Bar Ilan University.
April 2023 - Equiangular lines via matrix projection, Combinatorics Seminar, The Hebrew University of Jerusalem.
December 2022 - A recent breakthrough on the union-closed conjecture, KU-Jerusalem Lunch Seminar
August 2022 - Equiangular lines and regular graphs, Random Structures and Algorithms, Gniezno.
March 2022 - Equiangular lines and regular graphs[YOUTUBE], Codes and Expansions (CodEx) Seminar.
February 2022 - Equiangular lines and regular graphs, Combinatorics, Physics and Probability Seminar, CMSA, Harvard University.
December 2021 - Equiangular lines and regular graphs, Combinatorics Seminar, The Hebrew University of Jerusalem.
November 2021 - Equiangular lines and regular graphs, Combinatorics Seminar, Tel Aviv University.
June 2021 - Equiangular lines and graph spectra, Combinatorics Research Seminar, The Free University of Berlin
December 2019 - Orthonormal representations of H-free graphs, TAU Combinatorics Seminar, Tel Aviv University.
September 2019 - The Minrank of Random Graphs over Arbitrary Fields, Discrete Mathematics Seminar, Princeton University.
July 2019 - The Minrank of Random Graphs over Arbitrary Fields, Random Structures and Algorithms, Zurich.
February 2019 - The Minrank of Random Graphs over Arbitrary Fields, Mittagsseminar, ETH Zurich.
October 2017 - Equiangular Subspaces, Mittagsseminar, ETH Zurich.
August 2017 - Equiangular Lines and Subspaces in Euclidean Spaces, Eurocomb, Vienna.
August 2017 - Ramsey Goodness of Bounded Degree Trees, Random Structures and Algorithms, Gniezno.
January 2017 - Equiangular Lines and Spherical Codes, Workshop on Combinatorics, Oberwolfach.
June 2016 - Ramsey Goodness of Bounded Degree Trees, SIAM Conference on Discrete Mathematics, Georgia State University.
April 2016 - Equiangular Lines, Mittagsseminar, ETH Zurich.
November 2014 - Noisy population recovery, CS Student Seminar, Courant Institute, NYU.
September 2012 - Extremal results for union-closed families, Discrete Mathematics Seminar, Rutgers University.
March 2012 - Extremal results for union-closed families, Algorithms, Combinatorics, and Optimization Seminar, Carnegie Mellon University.