## Seminars and Colloquium

#### Andrea Collevecchio (Monash University (Australia))Probability Seminar

Boostrap Random Walk

#### Jinhae Park (Chungnam National University)MathSci Seminar

Current Trends in Mathematical Thoery of Liquid Crystals

#### George Yin (Wayne State University (USA))Probability Seminar

Two-time-scale Markovian Systems and Applications

#### George Yin (Wayne State University)MathSci Seminar

Switching Diffusions and Applications

#### Sungmun Cho (Kyoto University)Number Theory Seminar

Reformulation of the Siegel series and intersection numbers

#### 이석봉 (대덕넷)NIMS Colloquium

위기의 시대, 지식인으로서 "나"의 자세는?

#### Jeon, Wonju (Department of Mechanical Engineering, KAIST)MathSci Seminar

Bridging the Gap between Math and Mechanics

## Conferences and Workshops

## Bookmarks

## Bulletin Boards

중3 수학 과외 선생님 모십니다. | 04. 06 | |

여학생 과외 원합니다. | 03. 07 | |

고교2학년생입니다. 수학선생님 원해요 | 11. 11 | |

대학원 입시 설명회 자료 좀 올려주시겠어요? | 06. 22 | |

모듈 형식과 타원 방정식에 대해서 질문합니다 | 11. 13 |

## Problem of the week

Suppose that \( z_1, z_2, \dots, z_n \) are complex numbers satisfying \( \sum_{k=1}^n z_k = 0 \). Prove that
\[
\sum_{k=1}^n |z_{k+1} - z_k|^2 \geq 4 \sin^2 \left( \frac{\pi}{n} \right) \sum_{k=1}^n |z_k|^2,
\]
where we let \( z_{n+1} = z_1 \).