### Date

2022年5月12日 (木) 16:00 18:00

Title: The level-set mean curvature flow equation versus the total variation flow equation

Abstract: The level-set mean curvature flow equation has been introduced to track an evolving hypersurface by its mean curvature after it develops singularities. A level-set of a solution of the level-set mean curvature flow equation moves its mean curvature. The total variation flow equation is often used to remove noise from images. Although these two equations look similar, analytic properties are quite different; the former equation is a local equation while the latter is a nonlocal equation. In this talk, we compare these two equations as well as a few applications.

Discussion Theme (for the 2nd part of the event) :

How to collaborate with researchers other than mathematicians

The colloquium will be held once a month online. Each event consists of a one-hour talk on mathematics followed by a one-hour diversity panel discussion session. Please register before May , 5 pm. Click here to register!

### Date

2022年4月11日 (月) 10:00 12:00

### In describing properties of disordered media, physicists have long been interested in the behaviour of random walks on random graphs that arise in statistical mechanics, such as percolation clusters and various models of random trees. Random walks on random graphs are also of interest to computer scientists in studies of complex networks. In ‘critical’ regimes, many of the canonical models exhibit large-scale fractal properties, which means it is often a challenge to describe their geometry, let alone the associated random walks. In this talk, I will describe an approach suitable for understanding various ‘low-dimensional’ models of random walks on random graphs that builds on the deep connections that exist between electrical networks and stochastic processes.

Part II Discussion Theme:

Working in different places, and especially in different countries, naturally leads one to draw comparisons. Through such, one learns more about the working cultures of each. After some brief general musings on this topic, I plan to share some of my experiences from the UK of working on a departmental committee that was responsible for staff welfare (including work-life balance and gender equality).

### Date

2022年2月22日 (火) 15:00 17:00

### The colloquium will be held once a month online. Each event consists of a one-hour talk on mathematics followed by a one-hour diversity panel discussion session. February speaker is Jun Kitagawa from Michigan State University.

In the mathematics part, we will hear an exciting overview talk for a general audience. In the discussion session, we will hear about the speaker's experience as a mathematician. You can take inspiration from them and exchange ideas with other participants in a small group. After the sessions are over, there will be a tea time where participants can chat freely.

### Date

2022年1月19日 (水) 15:00 17:00

### The colloquium will be held once a month. It will be held online for the time being. Each event consists of a one-hour talk on mathematics followed by a one-hour diversity panel discussion session. Please register before January 14, 5 pm. Click here to register!

In the mathematics part, we will hear an exciting overview talk for a general audience. January speaker is Ade Irma Suriajaya from Kyushu University. In the discussion session, we will hear about the speaker's experience as a mathematician. You can take inspiration from them and exchange ideas with other participants in a small group. After the sessions are over, there will be a tea time where participants can chat freely.

Part I Expository math talk 3-4 pm

Speaker: Ade Irma Suriajaya Kyushu University

Talk Title : Goldbach’s Conjecture and the Riemann Hypothesis in Number Theory, and Their Relations to Zeta Functions

Abstract: Number Theory has a very long history that dates back to thousands of years ago. The main goal of this study is to understand properties of numbers which can essentially be reduced to understanding prime numbers. Number Theory has evolved over time and yet we are still left with several important old problems. Among, Goldbach’s conjecture which is celebrating its 280th anniversary this year (by the time of my talk in 2022) and the Riemann hypothesis which is now over 160 years old remain unsolved. In this talk, I would like to explain what these problems are about and briefly introduce a few recent works which are related to them, especially how the distribution of zeros of the Riemann zeta function comes into play. My talk will be given in the perspective of Analytic Number Theory.

Abstract:  Part II Diversity Panel Discussion 4-5 pm

### Date

2021年11月24日 (水) 15:00 17:00

### This colloquium will be held once a month. It will be held online for the time being. Each event consists of a one-hour talk on mathematics followed by a one-hour diversity panel discussion session.

In the mathematics part, we will hear an exciting overview talk for a general audience. November speaker is Masato Mimura from Tohoku University. In the discussion session, we will hear about the speaker's experience as a mathematician, especially in choosing fields of research. You can take inspiration from them and exchange ideas with other participants in a small group. After the sessions are over, there will be a tea time where participants can chat freely.

You can join Part I only or both parts of the colloquium. Please register before November 19, 5 pm. Click here to register!

Part I Expository math talk 3-4 pm

Speaker: Masato Mimura 見村万佐人 (Tohoku University 東北大学)

Talk Title : The Green--Tao theorem for number fields

Abstract:  The celebrated Green--Tao theorem states that an upper dense subset of the set of rational primes contains arbitrarily long arithmetic progressions. Later, Tao proved that an upper dense subset of the set of Gaussian primes, namely, prime elements in the integer ring $\mathbb{Z}[\sqrt{-1}]$ of the number field $\mathbb{Q}(\sqrt{-1})$ contains arbitrarily shaped constellations. (We will explain the precise statement in the talk.) In the paper, Tao asked whether the same conclusion holds in the setting of arbitrary number fields. In this joint work with Wataru Kai (Tohoku U.), Akihiro Munemasa (Tohoku U.), Shin-ichiro Seki (Aoyama Gakuin U.) and Kiyoto Yoshino (Tohoku U.), we answer Tao's question in the affirmative. We have an application to the setting of a binary quadratic form. More precisely, given a form $F$, we study combinatorics on the set of pair of integers $(x,y)$ for which $F(x,y)$ is a rational prime. No serious background of number theory is required for this talk.

Part II Diversity Panel Discussion 4-5 pm

### Date

2021年10月21日 (木) 9:00 11:00

The colloquium will be held once a month. It will be held online for the time being. Each event consists of a one-hour talk on mathematics followed by a one-hour diversity panel discussion session.

In the mathematics part, we will hear an exciting overview talk for a general audience. October speaker is Megumi Harada, Professor of McMaster University. In the discussion session, we will hear about the speaker's personal journey as a mathematician. You can take inspiration from them and exchange ideas with other participants in a small group. After the sessions are over, there will be a tea time where participants can chat freely.

You can join Part I only or both parts of the colloquium. Please register before Oct 18th, 5 pm. Click here to register!

### Date

2020年4月10日 (金) 14:30 16:30

Speaker: Dr. Sadovski is a member of this unit (visit his page)

### Date

2020年3月6日 (金) 9:30 11:30
Speaker: Mr. Ryusei Maeda is a 3rd year undergratuate student at University of Tokyo and is currently visiting OIST as a research intern.
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### Date

2020年2月21日 (金) 10:00 12:00

Speaker: Mr. Ryusei Maeda is a 3rd year undergratuate student at University of Tokyo and is currently visiting OIST as a research intern.

### Date

2020年2月14日 (金) 10:00 12:00
Speaker: Mr. Ryusei Maeda is a 3rd year undergratuate student at University of Tokyo and is currently visiting OIST as a research intern.