# KCL2019.08

KAIST Combinatorics Lab. Workshop

It is a triannual (three-times-a-year) seminar organized by academic genealogy from Professor Dongsu Kim in * KAIST Combinatorics Laboratory*, which KCL stands for. The aim of this seminar is to bring together active combinatorialists to discuss recent and prospective advances in

*and related areas. The style of talk tends to be less formal.*

**algebraic combinatorics**### Information

Information

**Title**KAIST Combinatorics Lab. Workshop 2019.08 (KCL2019.08)**Date**August 12 (Monday), 2019**Venue**Room 31318, Sungkyunkwan University, Suwon**Web**http://kaist.combinatorics.kr/2019-08

### Program

Program

**12:00 - 13:55**Welcome reception**13:55 - 14:00**Opening Address / Message from Dennis**14:00 - 16:00**Lecture 1 by Seunghyun Seo**Title.**Combinatorics on hyperplane arrangements.**Abstract.**A hyperplane arrangement is a collection of finitely many affine hyperplanes in some vector space (which for us will usually be over the real numbers.) We will give an introduction to the theory of hyperplane arrangements, focusing on their combinatorial properties. Topics will include the number of regions, intersection lattices, characteristic polynomials, and graphical arrangements. Some special arrangements will be analyzed, such as the braid, Catalan, Shi and Linial arrangements. We also present some recent progress on calculating characteristic polynomials of certain hyperplane arrangements.

**16:00 - 16:30**Coffee Break**16:30 - 17:30**Lecture 2 by U-keun Song**Title.**Rational generating functions**Abstract.**In this talk, we will review a general class of generating functions which is called rational generating functions. We will see a well-known role of rational generating functions about linear homogeneous Diophantine equations. And as an application, we will enumerate the number of nonnegative integer matrices such that every row and column sums are the same, namely, magic squares.

**17:30 - 17:55**Lightning Talks (about 3 minutes for each)**17:55 - 18:00**Closing Remarks**18:00 - 20:00**Dinner

### Participants

Participants

- Dongsu Kim, KAIST
- Seunghyun Seo, Kangwon National University
- Heesung Shin, Inha University
- Jang Soo Kim, Sungkyunkwan University
- Sun-mi Yun, Sungkyunkwan University
- U-keun Song, Sungkyunkwan University
- Jihyeug Jang, Sungkyunkwan University

- Taehyun Eom, KAIST

- Sangwook Kim, Chonnam National University
- JiSun Huh, Sungkyunkwan University
- Minho Song, Sungkyunkwan University
- SoHyeon Gyeong, Sungkyunkwan University

### Organizer

Organizer

- Jang Soo Kim, Sungkyunkwan University

### Host and Sponsor

Host and Sponsor

- Sungkyunkwan University
- Applied algebra and Optimization Research Center (AORC)
- National Research Foundation