I am one of the members organizing Incheon Combinatorics Seminar. We organize meetings in Thursday (Incheon National University, Inha University) or Friday (SUNY Korea) for this spring semester. We are happy to invite you to give a talk. Please e-mail me if you are interested in.

DATE : 11th, Oct, 2018 (10am-3pm)

There will be a one-day graph theory workshop at INU. Detailed information can be found at http://ojkwon.com/seminar/inugraph/.

DATE : 5th, Apr, 2018 (4-5pm).

TITLE: Sharp bound on the number of maximal sum-free subsets of integers

SPEAKER : Hong Liu

DATE : 19th, Apr, 2018 (4:20-5:10pm).

TITLE: Forbidding induced even cycles in a graph: typical structure and counting

SPEAKER : Jaehoon Kim

ABSTRACT : We determine, for all k≥6, the typical structure of graphs that do not contain an induced 2k-cycle. This verifies a conjecture of Balogh and Butterfield. Surprisingly, the typical structure of such graphs is richer than that encountered in related results. The approach we take also yields an approximate result on the typical structure of graphs without an induced 8-cycle or without an induced 10-cycle.

DATE : 12th, June, 2018 (4:00-4:50pm).

TITLE: Helly type theorems in combinatorics

SPEAKER : Minki Kim

ABSTRACT : Helly’s theorem is one of the most well-known and fundamental result about intersection patterns of convex in Euclidean spaces. It asserts that for a finite family $\mathcal{F}$ of convex sets in $\mathbb{R}^d$, if every $d+1$ or fewer members of $\mathcal{F}$ have a point in common, then all members of the family $\mathcal{F}$ have a point in common. There are a remarkable number of variants and applications of Helly’s theorem, and these results are called Helly type theorems. In this talk, I will give a brief overview on classical Helly type theorems, and introduce some recent generalizations of Helly’s theorem.