Ingyu Baek

Yonsei University

undergraduate (2022-)

• B.S. Computer Science and Engineering

• B.S. Mathematics

• Internship at Theory of Computation lab (June 2023-August 2024)

• Internship at Artificial Intelligence and Information Systems Lab (September 2024- October 2024)

• Internship at Combinatorics Lab (November 2024-)

Seoul Science High School

(2019-2021)

• Universal Rewriting Rules for the Parikh Matrix Injectivity Problem, with Joonghyuk Hahn, Yo-Sub Han and Kai Salomaa, In Proceedings of the 28th International Conference on Developments in Language Theory (DLT'24), LNCS 14791, 68--81, 2024

The Parikh matrix is a morphism from the monoid of words to matrices. Unlike Parikh vector (i.e. abelianization) which captures how many times specific character has appeared in a given word, Parikh matrix counts more sophisticated combinatorial patterns of the word. Since the introduction of the Parikh matrix, how sharp the Parikh matrix identifies the given word was considered as a major research interest. 

This paper provides the first general characterization of when two words have the same Parikh matrix, which has been open for more than 20 years. Previously, the characterization was known only for the alphabet of size 2 or 3. The extended version of this paper is under submission.

2025 Combinatorics Workshop [LINK]

• (August 18, 2025) Contributed Talk: Counting loose odd cycles in dense hypergraphs

This talk is about joint work with Joonkyung Lee. Preprint concerning the contribution of this talk is not yet uploaded on arXiv.

DAISY (Discrete Analysis & Insights Seminar at Yonsei) [LINK]

• (2025 Sep 11) Sparse graph limits, entropy maximization and transitive graphs. (paper by Balázs Szegedy)

  • We study an information theoretic homomorphism density, which is a novel idea shown in the paper. Using information theoretic arguments and constructions, we followed the main contribution of this paper, which implies that in order to prove of disprove Sidorenko's conjecture, it is enough to show for the edge-vertex transitive target graphs. 

• (2025 Jul 4) Probabilistic coupling method.

  • (Note) Sam Spiro, Methods in Extremal Combinatorics: Chapter 7, Coupling

  • Oliver Riordan, Random cliques in random graphs and sharp thresholds for F-factors

• (2025 Apr 11) Equiangular lines with a fixed angle. (paper by Zilin Jiang, Jonathan Tidor, Yuan Yao, Shengtong Zhang, and Yufei Zhao)

• (2025 Feb 26) The slice rank polynomial method.

  • (Lecture note) Lisa Sauermann, Algebraic Methods in Extremal Combinatorics (transcribed by Andrew Lin)

• (2024 Dec 30) PRIMES is in P. (paper by Manindra Agrawal, Neeraj Kayal, and Nitin Saxena)

Yonsei CS theory student group [LINK]

Summer 2024

• Universal rewriting rules for the Parikh Matrix injectivity problem

Winter 2024

• String edit distance 

Fall 2023

• Quantum automata cannot detect biased coins, even in the limit, 

• Reference: [1] 

28th International Conference on Developments in Language Theory (DLT 2024) [LINK]

• (14, August) Universal rewriting rules for the Parikh Matrix injectivity problem

• 2025 combinatorics workshop

• 2025 Korean Student Combinatorics Workshop

• 2025 IBS summer school Frontiers of Combinatorics

• DLT 2024: Developments in Language Theory