On October 22, 2020, Chun-Hung Liu (劉俊宏) from Texas A&M University gave a talk on his recent work answering several open problems on the asymptotic dimension of several graph classes at the Virtual Discrete Math Colloquium. The title of his talk was “Asymptotic dimension of minor-closed families and beyond“.

## Joonkyung Lee (이준경) gave a talk on norms defined from graphs at the Discrete Math Seminar

On October 21, 2020, Joonkyung Lee (이준경) from University College London gave a talk at the Discrete Math Seminar on norms defined from graphs motivated by Sidorenko’s conjecture and Gowers norms on extremal combinatorics, unifying two seemingly different concepts of real-norming graphs and complex-norming graphs. The title of his talk was “On graph norms for complex-valued functions“. Joonkyung Lee will stay at the IBS discrete mathematics group for several weeks from October 19.

## The IBS Discrete Mathematics Group (DIMAG) Postdoctoral Research Fellowship (Due: December 5, 2020)

The IBS Discrete Mathematics Group (DIMAG) in Daejeon, Korea invites applications for one postdoctoral research fellowship position.

URL: https://dimag.ibs.re.kr/hiring/

DIMAG is a research group that was established in December 1, 2018 at the Institute for Basic Science (IBS), led by Prof. Sang-il Oum. DIMAG is located at the headquarters of the Institute for Basic Science (IBS) in Daejeon, South Korea, a city of 1.5 million people.

The position is available for individuals who are within the first five years after obtaining their Ph.D at the date of appointment or be expected to obtain a Ph.D within three months from the date of appointment. Successful candidates for postdoctoral research fellowship positions will be new or recent Ph.D.’s with outstanding research potential in all fields of **discrete mathematics** with emphasis on **structural graph theory, extremal graph theory, combinatorial optimization, matroid theory, or fixed-parameter tractable algorithms**.

This appointment is for two years, and the starting salary is no less than KRW 57,000,000. The appointment is one time renewable up to 3 years in total contingent upon the outstanding performance of the researcher. The expected appointment date is September 1, 2021. This is a purely research position and will have no teaching duties.

A complete application packet should include:

- AMS standard cover sheet (preferred) or cover letter (PDF format)
- Curriculum vitae including a publication list (PDF format)
- Research statement (PDF format)
- Consent to Collection and Use of Personal Information (PDF file)
- At least 3 recommendation letters

For full consideration, applicants should email items 1, 2, 3, and 4 and arrange their recommendation letters emailed to **dimag@ibs.re.kr** by **December 5, 2020, Saturday**.

Recommendations letters forwarded by an applicant will not be considered.

DIMAG encourages applications from individuals of diverse backgrounds.

*In the unlikely event of closing the Center, the employment contract will be terminated accordingly. For Korean citizens who have not yet completed their military duty: IBS는 병역특례지정기관입니다. IBS is a designated institute for alternative military service.*

## Minki Kim (김민기) gave a talk on the collapsibility of the complex of vertex sets not containing independent sets of fixed size at the Discrete Math Seminar

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“.