2020 Combinatorics Workshop (2020 조합론 학술대회) was held on August 24 online

On August 24, Monday, the 2020 Combinatorics Workshop (2020 조합론 학술대회) was held online due to the COVID-19 pandemic. This local workshop series began in 2004 and has been continued to be one of the biggest annual gathering of people in combinatorics located in Korea. Due to the COVID-19 pandemic, it has been reduced to a one-day online conference on Zoom. It was hosted by Kyung Hee University and IBS Discrete Mathematics Group.

The workshop website: https://cw2020.combinatorics.kr

There were 5 invited speakers.

  • Sejeong Bang (방세정), Yeungnam University, Geometric distance-regular graphs
  • Ringi Kim (김린기), KAIST, Decomposing planar graphs into graphs with degree restrictions
  • Sangwook Kim (김상욱), Chonnam National University, Combinatorics of lattice path matroid polytopes
  • Jinyoung Park (박진영), Institute for Advanced Study, Tuza’s Conjecture for random graphs
  • Jongyook Park (박종육), Kyungpook National University, On distance-regular graphs with induced subgraphs $K_{r,t}$

There were 4 contributed talks.

  • Byung-Hak Hwang (황병학), Seoul National University, Acyclic orientation polynomials
  • Jaeseong Oh (오재성), Seoul National University, On linearization coefficients of q-Laguerre polynomials
  • Jun Seok Oh (오준석), Incheon National University, An inverse Erdős-Ginzburg-Ziv theorem for finite groups
  • Tuan Tran, IBS Discrete Mathematics Group, The singularity of random combinatorial matrices

2020 Combinatorics Workshop

Combinatorics Workshop (조합론 학술대회) is the biggest annual conference in combinatorics in Korea. It was firstly held in 2004 by the Yonsei University BK21 Research Group. It has been advised by the committee of discrete mathematics of the Korean Mathematical Society since 2013. The aim of this workshop is to bring active researchers with different backgrounds to discuss recent and prospective advances in combinatorics and related areas.

Originally, we planned an offline workshop. However, COVID 19 is more spreading and many participants are worried about attending an offline conference. So the schedule and venue are changed as an online workshop with Zoom. I hope that all participants generously understand this sudden change.

Invited Speakers

Contributed speakers

  • Byung-Hak Hwang (황병학), Seoul National University
  • Jaeseong Oh (오재성), Seoul National University
  • Jun Seok Oh (오준석), Incheon National University
  • Tuan Tran, Institute for Basic Science (IBS)

More information is available on the website https://cw2020.combinatorics.kr.

Ringi Kim (김린기), The strong clique number of graphs with forbidden cycles

The strong clique number of a graph $G$ is the maximum size of a set of edges of which every pair has distance at most two.

In this talk, we prove that every  $\{C_5,C_{2k}\}$-free graph has strong clique number at most $k\Delta(G)-(k-1)$, which resolves a conjecture by  Cames van Batenburg et al. We also prove that every $C_{2k}$-free graph has strong clique number at most $(2k−1)\Delta(G) + (2k−1)^2$, improving the previous known upper bound $10k^2 (\Delta(G)-1)$ due to  Cames van Batenburg et al. This is joint work with Eun-Kyung Cho, Ilkyoo Choi, and Boram Park.