The Discrete Math Seminar at Iowa State University is held on Thursdays at 2:10-3:00 pm in Carver 401 .
Some old talks are available on YouTube.
The seminar is organized by Grace McCourt and Bernard Lidický.
Jan 29 Ramón Iván García Alvarez
Title: Density of rainbow triangles and properly colored $K_4$’s
Abstract: T. W. Chao and H.-H. H. Yu showed in 2023 that a graph with $R$ red, $G$ green, and $B$ blue edges has at most $(2RGB)^{1/2}$ rainbow triangles. They proved this bound using entropy. In this talk, I will present a fully computer-free flag-algebra proof of their result, along with a translation of the argument into a classical counting proof. The ideas in our proof lead to an even shorter entropy proof. In addition, I will discuss a similar result that gives a sharp upper bound on the number of properly $3$-edge-colored $K_4$'s in graphs with $R$ red, $G$ green and $B$ blue edges. Joint work with József Balogh, Peter Bradshaw and Bernard Lidický.
Feb 5 Owen Henderschedt
Feb 10 Daniel Kráľ (colloquium)
Title: Analytic approach to extremal combinatorics
Abstract: Analytic tools to represent and study large discrete structures provided by the theory of combinatorial limits led to new views on a wide range of topics in mathematics and computer science. In this talk, we will briefly introduce the theory of combinatorial limits and showcase its methods on specific problems from Ramsey theory - Ramsey theory studies the existence of well-behaved substructures as given in the following classical statement proven by Ramsey in 1930: if N is sufficiently large, then for any partition of k-tuples of N points into finitely many classes, there exist n points such that all k-tuples formed by these n points belong to the same class. We will study quantitative versions of Ramsey type statements and present a solution of a 30-year-old problem on the existence of high chromatic graphs with small Ramsey multiplicity. In relation to general questions on the interplay of combinatorial limits and extremal combinatorics, we will present, among others, a counterexample to a conjecture of Lovász on finitely forcible optima of extremal problems.
Feb 12 (No seminar)
Feb 19 Filip Kučerák
Feb 26
Mar 5
Mar 12 Tung Nguyen (zoom)
Mar 19 (spring break)
Mar 26
Apr 2 Francis Su (colloquium)
Apr 9
Apr 16
Apr 23
Apr 30
May 7
May 14 (exam week)
Mar 9-16 57th Southeastern International Conference on Combinatorics, Graph Theory & Computing (Boca)
Mar 27-29 Graduate Students Combinatorics Conference (Chicago)
May 2-3 The 11th Lake Michigan Workshop on Combinatorics and Graph Theory (Notre Dame)
May 16-17 34th Cumberland Conference on Combinatorics, Graph Theory, and Computing (Auburn)
Jun ~9 to ~12 EXCILL 5 (Urbana-Champaign)
Jun 22-25 SIAM Conference on Discrete Mathematics (San Diego)
Aug 5-8 MAA Mathfest (Boston)
Aug 19-21 Graph Drawing (Ontario, Canada)
TBA (Summer) Graduate Research Workshop in Combinatorics (GRWC 2026)