On June 27, 2023, Chong Shangguan (上官冲) from Shandong University gave a talk at the Discrete Math Seminar on the maximum number of colors of hats so that at least one of the players can correctly guess his or her hat color while only seeing the colors of their neighbors on a graph. The title of his talk was “the hat guessing number of graphs.”

## Welcome Zhuo Wu from the Univeristy of Warwick, a new visiting student of ECOPRO

The IBS Discrete Mathematics Group welcomes Zhuo Wu (吴茁) from the University of Warwick, a new visiting student of the IBS Extremal Combinatorics and Probability Group (ECOPRO). He will stay with us for 1 year.

## Welcome Chuandong Xu from Xidian University, a new visiting scholar in the IBS Discrete Mathematics Group

The IBS Discrete Mathematics Group welcomes Dr. Chuandong Xu, a new visiting scholar from Xidian University, China. He is visiting the IBS Discrete Mathematics Group for 1 year from June 21, 2023. He is a lecturer at Xidian University and received his Ph.D. from Northwestern Polytechnical University in China in 2016.

## The IBS president visited DIMAG and ECOPRO

On June 21, 2023, President Do Young Noh of IBS visited the Discrete Mathematics Group (DIMAG) and the Extremal Combinatorics and Probability Group (ECOPRO), engaging in discussions with members of both groups.

## Guanghui Wang gave a talk on the maximum number of edges in uniformly dense hypergraphs with a forbidden subgraph at the Discrete Math Seminar

On June 20, 2023, Guanghui Wang (王光辉) from Shandong University gave a talk at the Discrete Math Seminar on the maximum number of edges in uniformly dense hypergraphs with a forbidden subgraph. The title of his talk was “Embeddings in uniformly dense hypergraphs.”

## Welcome Dong Yeap Kang (강동엽), a new member of the IBS Extremal Combinatorics and Probability Group

The IBS discrete mathematics group welcomes Dr. **Dong Yeap Kang (강동엽)**, a new research fellow at the IBS Extremal Combinatorics and Probability Group from June 16, 2023. Dr. Kang received his Ph.D. from the Department of Mathematical Science at KAIST in 2020 under the supervision of Prof. Sang-il Oum. Before joining the IBS Extremal Combinatorics and Probability Group, he was a research fellow at the University of Birmingham. He won the IBS Young Scientist Fellowship.

## Minho Cho gave a talk on the maximum size of a pure pair in graph classes at the Discrete Math Seminar

On June 13, 2023, Minho Cho (조민호) from the IBS Extremal Combinatorics and Probability Group gave a talk at the Discrete Math Seminar on determining the maximum size of a pure pair in graph classes regarding the strong Erdős-Hajnal property. The title of his talk was “Strong Erdős-Hajnal property on chordal graphs and its variants.”

## Invited minisymposium on the structural graph theory at CanaDAM2023

Sang-il Oum and Sebastian Wiederrecht organized an invited minisymposium at the CanaDAM 2023 (Canadian Discrete and Algorithmic Mathematics) held in Winnipeg, Canada on June 5-8, 2023. Here is the list of speakers for the minisymposium.

**Paul Wollan**(Sapienza University of Rome):*“Tree decompositions into subgraphs of bounded radius”***Jan Kurkofka**(University of Birmingham):*“Canonical decompositions of*3*-connected graphs”***Stephan Kreutzer**(Technische Universität Berlin):*“Towards a structure theorem for digraph minors”***Sebastian Wiederrecht**(IBS Discrete Mathematics Group):*“Universal obstructions in graph minors”***Youngho Yoo**(Texas A&M University):*“Erdős-Pósa property in undirected group-labelled graphs”***Eunjung Kim**(LAMSADE, Université Paris-Dauphine):*“When twin-width is the right measure”***Chun-Hung Liu**(Texas A&M University):*“Minor-closed families are defectively perfect”***Raphael Steiner**(ETH Zürich):*“Digraphs of large out-degree: problems and new results”***J. Pascal Gollin**(IBS Discrete Mathematics Group):*“A structural theory for odd minors”*

## Suyun Jiang (江素云) gave a talk on the maximum number of edges in a connected graph without a fixed tree at the Discrete Math Seminar

On May 30, 2023, Suyun Jiang (江素云) from Jianghan University gave a talk on the maximum number of edges in a connected graph without a fixed tree at the Discrete Math Seminar. She is currently a visiting scholar at the IBS Extremal Combinatorics and Probability Group. The title of her talk was “How connectivity affects the extremal number of trees.”