# Seminar Report

## Math Seminar Talk by Dr. Martin Skrodzki, February 7, 2020.

2020-02-12

Dr. Martin Skrodzki, who stays at RIKEN iTHEMS as a postdoctoral researcher for the year 2020, gave a talk at the Math Seminar on February 7, 2020. The title of his talk was "Solved and open problems regarding the neighborhood grid data structure". He began with introducing the k-d tree for a finite set with coordinates in the plane and explained that by using this tree one can find the nearest point from a given point in a reasonable time. Then, he looked at the neighborhood grid data structure introduced by Joselli et al. in 2009, which is an n times n matrix filled by pairs of numbers (f(i,j),g(i,j)) where f and g are surjections to the set of numbers from 1 to n squared. He gave the definition of a stable state and explained that any grid data structure can be stabilized and that stabilization can be done in a short time using parallel computation. He explained the correspondence between a generic set of n squared points in the plane and stable grid data structures, and discussed several open questions around this correspondence. The talk was very accessible for everyone and the participants enjoyed it very much.

# Seminar Report

## Biology Talk by Dr. Yasuo Yasui, February 5, 2020.

2020-02-13

On February 5, 2020, Dr. Yasuo Yasui, a plant geneticist from Kyoto University, gave a talk on his research on buckwheat (=soba) genetics. First, he explained how the current food supply of the world is heavily dependent on a very small number of plants, and that there is a pressing need to increase the yield of many other non-major crops, including buckwheat. He argued that now we have the tools to tackle this problem thanks to the advance in genome sequencing technologies, and that data science, computer science, and mathematical science have important roles to play. He then presented his previous research on buckwheat genetics and genomics, such as the identification of certain genes in buckwheat that are important for buckwheat breeding. He also showed some slides from field trips in South China (mainly Yunnan province) to collect wild buckwheat species, and explained his ongoing research in trying to understand the origin and domestication process of buckwheat, which is a joint effort with Jeffrey Fawcett from iTHEMS, and other researchers in Japan, China, and the UK. The talk was aimed at non-biologists, and many non-biologists from iTHEMS were able to join and ask many questions.

# Upcoming Events

## Seminar

### Mining for Dark Matter substructure: Learning from lenses without a likelihood

February 17 at 14:00 - 15:30, 2020

Dr. Johann Brehmer (Postdoctoral Researcher, New York University)

Dr. Brehmer gives us a talk about a method to deduce DM small structures. Please join us!

Venue: #424-426, Main Research Building, RIKEN

Event Official Language: English

## Colloquium

### The 11th MACS colloquium

February 19 at 15:00 - 17:30, 2020

Prof. Hiroyuki Hata (Professor, Graduate School of Science, Kyoto University)

15:00 ティータイム

15:15 弦の場の理論とその数理 畑 浩之氏 （理学研究科 物理学・宇宙物理学専攻 教授）

16:40 2019年度MACS成果報告会

The 11th MACS colloquium is supported by iTHEMS. It will be broadcasted to Wako, but if you can join the colloquium physically in Kyoto, that would be better. iTHEMS provides good confectionery at Kyoto!

Venue: Lecture room #401, Graduate School of Science Building No 6, Kyoto University

Event Official Language: Japanese

## Seminar

### Index of the Wilson-Dirac operator revisited: a discrete version of Dirac operator on a finite lattice

February 25 at 16:00 - 18:10, 2020

Dr. Mikio Furuta (Professor, The University of Tokyo)

Venue: Seminar Room #160, 1F Main Research Building, RIKEN

Event Official Language: English

## Workshop

### [CANCELLED] The 2nd KUIAS-Heidelberg-RIKEN iTHEMS joint WS "Mathematical Sciences and Medicine"

March 20 - 21, 2020

Venue: Kyoto University Institute for Advanced Study (KUIAS)

Event Official Language: Japanese

# Upcoming Visitor

March 3 - 31, 2020 ## Dr. Gordon BaymSenior Visiting Scientist, iTHEMS Research fields: Quantum Many-body Theory Visiting Place: RIKEN Wako Campus |

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