On September 8, 2020, Rutger Campbell from the IBS Discrete Mathematics Group presented a talk on various results on the real representability of matroids at the Discrete Math Seminar. The title of his talk was “Disasters in abstracting combinatorial properties of linear dependence“.

## Junguk Lee (이정욱) from KAIST gave an intensive lecture on the stability and NIP in the model theory at the Discrete Math Seminar for two days

On August 31 and September 1, 2020, Junguk Lee (이정욱) from KAIST gave a 6-hour-long talk on the model theory with the focus on the stability, NIP, and the VC dimension at the Discrete Math Seminar. The title of his talk was “a quick introduction to stability and NIP”. The part 1 “basics” and the part 2 “stability” were coved on August 31, for 1.5 hours each, and the part 3 “NIP” was covered on September 1 for 3 hours (10:30-11:30, 3:00-4:00, 4:10-5:10).

## Welcome Jinha Kim (김진하) and Minki Kim (김민기), new members of IBS Discrete Mathematics Group

The IBS Discrete Mathematics Group welcomes Dr. **Jinha Kim (김진하)** and Dr. **Minki Kim (김민기)**, new research fellows at the IBS Discrete Mathematics Group from September 1, 2020.

**Jinha Kim (김진하)** received his Ph.D. from the Department of Mathematics at Seoul National University in 2019 under the supervision of Prof. Woong Kook. Until recently, she was a postdoctoral fellow at Technion in Israel. She is interested in combinatorics, discrete geometry, topological combinatorics, and graph theory.

**Minki Kim (김민기)** received his Ph.D. from the Department of Mathematical Sciences at KAIST in 2018 under the supervision of Prof. Andreas Holmsen. Until recently, he was a postdoctoral fellow at Technion in Israel. He is interested in discrete geometry, topological combinatorics, and graph theory.

## Welcome Prof. Jeong Ok Choi (최정옥) from GIST, a new Visiting Research Fellow in the IBS discrete mathematics group

The IBS Discrete Mathematics Group welcomes Prof. Jeong Ok Choi (최정옥) from GIST, Gwangju, Korea. She will visit the IBS Discrete Mathematics Group for 1 year until August 31, 2021 during her sabbatical leave from GIST. She received her Ph.D. from University of Illinois at Urbana-Champaign under the supervision of Prof. Douglas West. She was a visiting assistant professor at Furman University and Trinity College. In 2011, she moved to GIST (Gwangju Institute of Science and Technology) in Gwangju, Korea as an assistant professor and she is currently an associate professor.

## Welcome Rutger Campbell and Debsoumya Chakraborti, new members of IBS Discrete Mathematics Group

The IBS discrete mathematics group welcomes Dr. **Rutger Campbell** and Dr. **Debsoumya Chakraborti**, new research fellows at the IBS discrete mathematics group from August 16, 2020.

**Rutger Campbell** received his Ph.D. from the Department of Combinatorics and Optimization at the University of Waterloo in 2020 under the supervision of Prof. Jim Geelen. He is interested in matroid theory and structural graph theory.

**Debsoumya Chakraborti** received his Ph.D. from the Program of Algorithms, Combinatorics, and Optimization at the Carnegie Mellon University in 2020 under the supervision of Prof. Po-Shen Loh. He is interested in extremal combinatorics, probabilistic combinatorics, and random graphs.

## Ben Lund gave a talk on the generalization of Beck’s theorem on the number of incidences between points and lines at the Discrete Math Seminar

On August 25, 2020, Ben Lund from IBS Discrete Mathematics Group presented a talk on his generalization of Beck’s theorem resulting lower bounds on the number of planes spanned by a set of points and its various applications. The title of his talk was “Point-plane incidence bounds“.

## 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*

## Tuan Tran gave a talk on the anti-concentration phenomena at the Discrete Math Seminar

On August 18, 2020, Tuan Tran from IBS Discrete Mathematics Group gave a talk on the anti-concentration phenomena and its consequences to the random matrix theory. The title of his talk is “Anti-concentration phenomena”.

## Welcome Ben Lund and Tuan Tran, new research fellows in the IBS Discrete Mathematics Group

The IBS discrete mathematics group welcomes Dr. **Ben Lund** and Dr. **Tuan Tran**, new research fellows at the IBS discrete mathematics group from August 1, 2020.

**Ben Lund** received his Ph.D. from the Department of Mathematics at Rutgers University in 2017 under the supervision of Prof. Shubhangi Saraf. Before joining the IBS, he was a postdoc at Princeton University and a postdoc at the University of Georgia.

**Tuan Tran** received his Ph.D. from the Department of Mathematics at the Freie Universität Berlin in 2015 under the supervision of Prof. Tibor Szabó. Before joining the IBS, he was a lecturer at Hanoi University of Science and Technology, a postdoc at ETH Zürich, and a postdoc at Czech Academy of Sciences. He won the IBS Young Scientist Fellowship.

## Yunbum Kook (국윤범) gave a talk on finding a small equivalence instance for the minimum edge-cut problem at the Discrete Math Seminar

On August 11, 2020, Yunbum Kook (국윤범) from KAIST presented his work on the existence of a *connectivity-c mimicking network*, which is a graph preserving the size of all minimum edge-cuts between any partition of a given set of terminals up to a constant c and an efficient algorithm to find one. The title of his talk was “Vertex Sparsification for Edge Connectivity”.