### Kevin Hendrey, Extremal functions for sparse minors

Room B232 IBS (기초과학연구원)

The extremal function $c(H)$ of a graph $H$ is the supremum of densities of graphs not containing $H$ as a minor, where the density of a graph is the ratio of the number of edges to the number of vertices. Myers and Thomason (2005), Norin, Reed, Thomason and Wood (2020), and Thomason and Wales (2019)

### Eunjin Oh (오은진), TBA

Room B232 IBS (기초과학연구원)

### Joonkyung Lee (이준경), TBA

Room B232 IBS (기초과학연구원)

### Jaehoon Kim (김재훈), 2-complexes with unique embeddings in 3-space

Room B232 IBS (기초과학연구원)

A well-known theorem of Whitney states that a 3-connected planar graph admits an essentially unique embedding into the 2-sphere. We prove a 3-dimensional analogue: a simply-connected 2-complex every link graph of which is 3-connected admits an essentially unique locally flat embedding into the 3-sphere, if it admits one at all. This can be thought of

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