## Sang-il Oum (엄상일) gave a talk at the Discrete Math Seminar on an explicit upper bound of the size of each obstruction for graphs of linear rank-width at most k and matroids of path-width at most k

On February 28, 2022, Sang-il Oum from IBS Discrete Mathematics Group and KAIST gave a talk at the Discrete Math Seminar on an explicit upper bound of the size of pivot-minor obstructions of graphs of linear rank-width at most k and the size of F-representable minor obstructions of matroids of path-width at most k. The title of his talk was “Obstructions for matroids of path-width at most k and graphs of linear rank-width at most k“.

## Welcome Prof. Hongseok Yang (양홍석) from KAIST, a new Visiting Research Fellow in the IBS Discrete Mathematics Group

The IBS Discrete Mathematics Group welcomes Prof. Hongseok Yang (양홍석) from the School of Computing, KAIST, Daejeon, Korea. He will visit the IBS Discrete Mathematics Group for 1 year from February 28, 2022 to February 24, 2023 during his sabbatical leave from KAIST. He received his Ph.D. from the University of Illinois at Urbana-Champaign in 2001 and was a University Lecturer, an Assistant Professor, and a Full Professor in the Department of Computer Science at the University of Oxford since May 2011. He moved to KAIST as a full professor in July 2017.

## Donggyu Kim (김동규) gave a talk on an analog of the theorem of Oxley and Wu on matroids for vertex-minors of graphs at the Discrete Math Seminar

On February 21, 2022, Donggyu Kim (김동규) from KAIST / IBS Discrete Mathematics Group gave a talk at the Discrete Math Seminar on an analog of the theorem of Oxley and Wu on matroids for vertex-minors of graphs. The title of his talk was “A stronger version of Tutte’s wheel theorem for vertex-minors“.

## Jinha Kim (김진하) gave a talk on the minimum size of a maximal independent set in a graph of bounded maximum degree at the Discrete Math Seminar

On February 15, 2022, Jinha Kim (김진하) from the IBS Discrete Mathematics Group gave a talk at the Discrete Math Seminar on the minimum size of a maximal independent set (or equivalently, an independent dominating set) in a graph of maximum degree at most $\Delta$. The title of her talk was “Independent domination of graphs with bounded maximum degree“.

## James Davies gave an online talk disproving Esperet’s conjecture on the polynomial 𝜒-boundedness of graph classes at the Virtual Discrete Math Colloquium

On February 10, 2022, James Davies from University of Waterloo gave an online talk at the Virtual Discrete Math Colloquium disproving Esperet’s conjecture on the polynomial 𝜒-boundedness of graph classes. The title of his talk was “Separating polynomial 𝜒-boundedness from 𝜒-boundedness“.

## Pascal Gollin gave a talk on the unified Erdős-Pósa type theorem for cycles in graphs whose edges are labelled by elements of multiple abelian groups at the Discrete Math Seminar

On February 8, 2022, Pascal Gollin from the IBS Discrete Mathematics Group gave a talk at the Discrete Math Seminar on the unified Erdős-Pósa type theorem for cycles in graphs whose edges are labelled by multiple abelian groups. The title of his talk was “A unified Erdős-Pósa theorem for cycles in graphs labelled by multiple abelian groups“.

## Bo Ning gave an online talk on the number of triangles and quadrilaterals in a graph with certain conditions on eigenvalues at the Virtual Discrete Math Colloquium

On January 27, 2022, Bo Ning (宁博) from Nankai University, China gave an online talk at the Virtual Discrete Math Colloquium on the number of 3-cycles and 4-cycles in a graph with certain conditions on eigenvalues. The title of his talk was “Substructures and eigenvalues of graphs: Triangles and quadrilaterals“.

기초과학연구원 수리및계산과학연구단 이산수학그룹
대전 유성구 엑스포로 55 (우) 34126
IBS Discrete Mathematics Group (DIMAG)
Institute for Basic Science (IBS)
55 Expo-ro Yuseong-gu Daejeon 34126 South Korea
E-mail: dimag@ibs.re.kr, Fax: +82-42-878-9209