On September 29, 2020, Minki Kim (김민기) from the IBS Discrete Mathematics Group presented his work on the collapsibility of the complex $I_n(G)$ of vertex sets of a graph $G$ not containing any $n$-vertex independent set at the Discrete Math Seminar. The title of his talk was “Complexes of graphs with bounded independence number“.

## Zihan Tan gave a talk on an improved bound for the grid minor theorem of Robertson and Seymour at the Virtual Discrete Math Colloquium

On September 24, 2020, Zihan Tan from University of Chicago gave an online talk about his recent work with Julia Chuzhoy on an improved bound for the grid minor theorem of Robertson and Seymour. They prove that every graph with no $g\times g$ grid minor has tree-width at most $O(g^{9}\operatorname{poly log}(g))$. The title of his talk was “Towards Tight(er) Bounds for the Excluded Grid Theorem“.

## Jinha Kim (김진하) gave a talk on her work on the collapsibility of the non-cover complexes of graphs at the Discrete Math Seminar

On September 22, 2020, Jinha Kim (김진하) from the IBS Discrete Mathematics Group presented her recent work on the collapsibility of the non-cover complexes of graphs at the Discrete Math Seminar. The non-cover complex of a graph is a simplicial complex consisting of subsets of vertices not covering all edges. The title of her talk was “Collapsibility of Non-Cover Complexes of Graphs“.

## Luke Postle gave a talk on the very recent improvement towards Hadwiger’s conjecture at the Virtual Discrete Math Colloquium

On September 17, 2020, Luke Postle from the University of Waterloo gave an online talk about his recent (another) breakthrough towards Hadwiger’s conjecture. The title of his talk was “Further progress towards Hadwiger’s conjecture“.

## Welcome Prof. Heesung Shin (신희성) from Inha University, a new Visiting Research Fellow in the IBS Discrete Mathematics Group

The IBS Discrete Mathematics Group welcomes Prof. Heesung Shin (신희성) from Inha University, Incheon, Korea. He will visit the IBS Discrete Mathematics Group for 1 year until August 31, 2021 during his sabbatical leave from Inha University. He received his Ph.D. from KAIST under the supervision of Prof. Dongsu Kim. He was a postdoctoral researcher at CNRS and a research assistant professor at POSTECH. In 2011, he moved as an assistant professor to Inha University, where he is currently a professor.

## Debsoumya Chakraborti gave a talk on the problem of maximizing the number of cliques in a graph of small maximum degree at the Discrete Math Seminar

On September 15, 2020, Debsoumya Chakraborti from the IBS Discrete Mathematics Group presented a talk on the extremal problem on the number of cliques in a graph of small maximum degree with a fixed number of edges. The title of his talk was “Maximum number of cliques in a graph with bounded maximum degree“.

## Sebastian Siebertz gave a talk on recent approaches to combine model theoretic and graph theoretic tools to derive structural and algorithmic results for classes of (finite) graphs at the Virtual Discrete Math Colloquium

On September 10, 2020, Sebastian Siebertz from University of Bremen gave an online talk about recent attempts to combine the model theory to the theory of dense graphs at the Virtual Discrete Math Colloquium. The title of his talk was “Rank-width meets stability“.

## Rutger Campbell gave a talk on the real representability of matroids at the Discrete Math Seminar

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.