We use YouTube Live to broadcast seminar talks live if the speaker agrees.

### Huy-Tung Nguyen, The average cut-rank of graphs

Room B232 IBS (기초과학연구원)

The cut-rank of a set X of vertices in a graph G is defined as the rank of the X×(V(G)∖X) matrix over the binary field whose (i,j)-entry is 1 if

### Jiseung Kim (김지승), Hardness and concrete security in cryptography

Room B232 IBS (기초과학연구원)

Computationally hard problems have been widely used to construct cryptographic primitives such as encryptions, digital signatures. For example, provably secure primitives are based on a reduction from the hardness problems.

Postponed

### Seymour is Seventy (postponed)

ENS de Lyon, Lyon, France

A conference honouring the seventieth birthday of Paul Seymour To be held in ENS de Lyon, France, June 15 - 19, 2020 Conference Website: https://dimag.ibs.re.kr/seymour70/ Sponsors: IBS Discrete Mathematics Group.

### Andreas Holmsen, Fractional Helly and topological complexity

Room B232 IBS (기초과학연구원)

The fractional Helly theorem is a simple yet remarkable generalization of Helly's classical theorem on the intersection of convex sets, and it is of considerable interest to extend the fractional Helly

### Seog-Jin Kim (김석진), Online DP-coloring of graphs

Room B232 IBS (기초과학연구원)

Online list coloring and DP-coloring are generalizations of list coloring that attracted considerable attention recently. Each of the paint number, $\chi_P(G)$, (the minimum number of colors needed for an online

### Ilkyoo Choi (최일규), Flexibility of Planar Graphs

Room B232 IBS (기초과학연구원)

Oftentimes in chromatic graph theory, precoloring techniques are utilized in order to obtain the desired coloring result. For example, Thomassen's proof for 5-choosability of planar graphs actually shows that two adjacent

Postponed

### Nonlinear Algebra in Daejeon (Postponed)

IBS Science Culture Center

Program Summer School @ KAIST (August 4-7, 2020) Discussion Weekend (August 8-9, 2020) Workshop @ IBS Science Culture Center (August 10-13, 2020) Website: https://dimag.ibs.re.kr/home/nonlinear/ Organizing Committee Insong Choe (Konkuk U.)

Postponed

### 2020 IBS Workshop on Extremal and Probabilistic Combinatorics (postponed)

Room B234 IBS (기초과학연구원)

Date August 24, 2020 - August 28, 2020 Arrival: August 23 Sunday. Departure: August 29, Saturday Venue Institute for Basic Science,  55 Expo-ro, Yuseong-gu, Daejeon, South Korea Invited Speakers Julia Böttcher, London School 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