Generalized Erdös and Obláth theorem for polynomial-factorial Diophantine equations

October 23 (Tue) at 10:30 - 11:30, 2018

Wataru Takeda (Nagoya University)

Diophantine equations are equations where only integer solutions are accepted. There are many types of Diophantine equations and many results are known. Our Diophantine equation is of the form x^n+y^n=m!. Erdös and Obláth showed that the Diophantine equation x^2+y^2=m! has only two positive integer solutions (x,y,m)=(1,1,2),(12,24,6). In this talk, the factorial function m! is replaced with a generalized factorial function Π(m) over number fields. Then whether there are infinitely many solutions or not depends on the number field. We give necessary and sufficient condition for existence of infinitely many solutions of x^2+y^2=Π(m). More generally, we introduce an observation for higher degree equation x^n+y^n=Π(m).

Venue: Large Meeting Room, 2F Welfare and Conference Building (Cafeteria)

Event Official Language: English

Theory of Operator Algebras (4th)

October 18 (Thu) at 15:30 - 17:00, 2018

Yosuke Kubota (Research Scientist, iTHEMS)

Venue: Seminar Room #160

Event Official Language: Japanese

Nerd Nite Tokyo

October 12 (Fri) at 20:00 - 22:00, 2018

Don Warren (Research Scientist, iTHEMS)

Don Warren will give a talk about fast radio bursts and impatient Australians. Please come join us on October 12, and consider giving a presentation about something you enjoy. It doesn’t have to be your main research topic; if you have an interesting hobby or side project, that could be fun as well. Price: ¥1000, but speakers get in free Food and drinks available at the event

Venue: Nagatacho GRID (2-5-3 Hirakawa-cho, Chiyoda-ku, Tokyo 102-0093)

Event Official Language: English

Economic Networks: a Physicist's View

October 3 (Wed) at 15:00 - 16:30, 2018

Hideaki Aoyama (Senior Visiting Scientist, iTHEMS / Professor, Graduate School of Science, Kyoto University)

Economic phenomena occur on networks formed by agents, such as firms and financial institutions. In order to understand the dynamic nature of economy, we need to understand structures of those networks and interactions between economic agents on it. In this talk, I will review several important research results on this theme, most of which uses Japanese rich, actual (not simulated) network data, including trade (production) network of about one million firms. Community structures, simulation of effect of natural disasters, new methodology required for such inquiry are some of the topics to be covered.

Venue: Large Meeting Room, 2F Welfare and Conference Building (Cafeteria)

Broadcast:R511, Computational Science Research Building / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

Event Official Language: English

Non-Hermitian phase transition from a polariton Bose-Einstein condensate to a photon laser

September 28 (Fri) at 13:30 - 17:00, 2018

Ryo Hanai (Osaka University)

Venue: Seminar Room #160

Event Official Language: Japanese

Introduction to Random Matrix Theory 2

September 26 (Wed) at 10:00 - 16:30, 2018

Taro Kimura

Venue: #435-437, Main Research Building

Event Official Language: Japanese

Introduction to Random Matrix Theory 1

September 25 (Tue) at 10:00 - 16:30, 2018

Taro Kimura

Venue: #435-437, Main Research Building

Event Official Language: Japanese

International Symposium on Quantum Fluids and Solids (QFS)

July 25 (Wed) - 31 (Tue), 2018

The International Symposium on Quantum Fluids and Solids (QFS) will be held at Ito International Research Center (IIRC) on Hongo campus of the University of Tokyo, Japan, from July 25 through 31, 2018. One of the sponsors of this conference is iTHEMS. The QFS series started forty-three years ago making it one of the oldest series of international conferences in the field of low temperature physics. It has historically been focusing on physics of liquid and solid helium and hydrogen. But in this century its scope is expanding widely from laser cooled cold atoms to topological matters. At QFS2018 in Tokyo, this trend will be continued and with even more interdisciplinary aspects emphasized between the traditional subjects and those in broader physical systems.

Venue: Ito International Research Center (IIRC), Hongo Campus, The University of Tokyo

Event Official Language: English

Number Theory Seminar: 3 Talks

July 24 (Tue) at 10:00 - 12:35, 2018

Masataka Ono (Keio University)
Shingo Sugiyama (Nihon University)
Yoshinosuke Hirakawa (Keio University)

This seminar is aimed at scientists in general, not only to mathematicians. 10:00-10:45 Title: Multiple zeta functions associated with 2-colored rooted trees Speaker: Dr. Masataka Ono (Keio University) Abstract: In our recent work, we introduced a combinatorial object and finite sum associated with them which we call finite multiple zeta values associated with 2-colored rooted trees and gave a unified interpretation to some types of finite multiple zeta values. In this talk, we introduce multiple zeta function associated with 2-colored rooted tree and discuss its analytic properties, for example, the possible singularities and functional equations. 10:55-11:40 Title: Modular forms and trace formulas with applications to equidistributions of their Fourier coefficients Speaker: Dr. Shingo Sugiyama (Nihon University) Abstract: Modular forms are interesting objects in number theory as they are related to arithmetic problems. Trace formulas of Hecke operators acting on modular forms are very useful tools to study arithmetic invariants: Fourier coefficients, special values of L-functions, Hurwitz class numbers. We will start fundamental notions on modular forms and trace formulas of Hecke operators for non-experts, and introduce our results on a generalization of Serre’s vertical Sato-Tate law. Some results in this talk are based on a joint work with Masao Tsuzuki (Sophia University). 11:50-12:35 Title: On a generalization of Dobinski's formula Speaker: Yoshinosuke Hirakawa (Keio University) Abstract: Dobinski's formula is a very classical formula, which expresses the Bell number as an infinite series. Here, the Bell number is the number of partitions of a finite set. Such a "combinatorial-analytic" formula should lead us to more beautiful number theory. In this talk, we introduce a generalization of Dobinski's formula by means of a certain multiple generalization of the exponential function.

Venue: Seminar Room #160

Event Official Language: English

Bell's Theorem, Entanglement, Quantum Teleportation and All That

July 19 (Thu) at 16:00 - 17:30, 2018

Anthony James Leggett (Professor, University of Illinois at Urbana-Champaign, USA)

iTHEMS-CEMS Joint Colloquium. Professor Leggett is widely recognized as a world leader in the theory of low-temperature physics, and his pioneering work on superfluidity was recognized by the 2003 Nobel Prize in Physics. Abstract: One of the most surprising aspects of quantum mechanics is that under certain circumstances it does not allow individual physical systems, even when isolated, to possess properties in their own right. This feature, first clearly appreciated by John Bell in 1964, has over the last half-century been tested experimentally and found (in most people's opinion) to be spectacularly confirmed. More recently it has been realized that it permits various operations which are classically impossible, such as "teleportation" and secure-in-principle cryptography. This talk is a very basic introduction to the subject, which requires only elementary quantum mechanics.

Venue: Okochi Hall

Broadcast:#311, Computational Science Research Building / SUURI-COOL (Kyoto) / 2F Seminar Room, AIMR Main Building

Event Official Language: English

The 9th RIKEN-Kyoto University Joint Data Assimilation Workshop

July 17 (Tue) at 13:30 - 17:30, 2018

If you plan to attend the workshop, please register by July 13. Hosted by Data Assimilation Research Team, RIKEN and Graduate School of Science, Kyoto University Co-hosted by iTHEMS, RIKEN

Venue: #809 Graduate School of Science Bldg. No 6, Kyoto University

Event Official Language: Japanese

Theory of Operator Algebras (3rd)

July 12 (Thu) at 15:30 - 17:00, 2018

Yosuke Kubota (Research Scientist, iTHEMS)

Venue: Seminar Room #160

Event Official Language: English

Introduction to Public-Key Cryptography (6th)

July 11 (Wed) at 10:30 - 12:00, 2018

Eren Mehmet Kıral (Visiting Researcher, RIKEN Center for Advanced Intelligence Project (AIP))

Venue: Seminar Room #160

Event Official Language: English

Introduction to topological band structure

July 6 (Fri) at 10:30 - 17:30, 2018

Tomoki Ozawa (Senior Research Scientist, iTHEMS)

In this seminar, I give an introduction to topological band structures. Topological band structure is the fundamental idea to understand phenomena such as the quantum Hall effect, topological insulators, and topological superconductors. Although originally found in fermionic electron systems, topological band structure is essentially a single-particle property, and thus the same phenomenon can arise also in bosonic systems. In fact, topological band structure does not even need quantum mechanics; topological band structure can arise in classical waves inside a periodic medium, such as electromagnetic waves or classical mechanical waves. In this seminar, I first give a brief introduction to key concepts in topological band structures, such as Berry curvature, Chern number, bulk-edge correspondence, and ten-fold way classification of topological insulators. I then explain how topological band structure can arise in classical systems, giving a brief introduction to the field of topological photonics and topological mechanics.

Venue: Seminar Room #160

Event Official Language: Japanese

iCeMS-iTHEMS Joint Workshop on Interdisciplinary Biology

July 4 (Wed) at 10:00 - 16:30, 2018

This is the first joint workshop between iCeMS (Kyoto Univ.) and iTHEMS (RIKEN). The WS is co-hosted by KUIAS (Kyoto Univ.), iTHEMS (RIKEN) and MACS Program (Kyoto Univ.). By exploring the forefront of experimental and mathematical biology, this workshop aims to stimulate novel research directions in these areas and strengthen the connection between Kyoto Univ. and RIKEN. Those who plan to attend the "get-together", please register before June 22 (Fri.) noon. Co-hosted by Kyoto University Institute for Advanced Study (KUIAS), Kyoto Univ. Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), RIKEN MACS Program (MACS), Kyoto Univ.

Venue: #201, Maskawa Building for Education and Research

Event Official Language: English

Topological Photonics and the four-dimensional quantum Hall effect

July 3 (Tue) at 15:00 - 17:00, 2018

Tomoki Ozawa (Senior Research Scientist, iTHEMS)

In this seminar, I will give an introduction to topological photonics, that is, the study of topological band structures and resulting topological phenomena in photonic systems. I will first review basic concepts of topological band structures, and then explain what it means to realize topological band structures in photonic systems. I will particularly emphasize some important differences with respect to solid-state electron systems. I then present some of my own works in topological photonics, such as the synthetic dimensions in photonic systems, which allows one to explore models and phenomena in high dimensions including the four-dimensional quantum Hall effect.

Venue: 1F Meeting Room, AIMR Main Building

Event Official Language: English

The 5th MACS Colloquium

July 3 (Tue) at 15:00 - 17:30, 2018

Keisuke Fujii (Program-Specific Associate Professor, Graduate School of Science, Kyoto University)
Takao Hirajima (Kyoto University)

15:00- Teatime 15:15- Talk by Dr. Keisuke Fujii (Kyoto University) 16:30- Talk by Prof. Takao Hirajima (Kyoto University) The 5th MACS colloquium supported by iTHEMS. It will be broadcasted to Wako by Skype, but if you can join the colloquium physically in Kyoto, that would be better. iTHEMS provides good cakes/cookies at Kyoto!

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

Broadcast:Seminar Room #160

Event Official Language: Japanese

Systems Biology of Cellular Rhythms

July 2 (Mon) at 15:00 - 16:30, 2018

Albert Goldbeter (Professor, Unit of Theoretical Chronobiology, Faculty of Sciences, Université Libre de Bruxelles, Belgium)

Rhythmic phenomena occur at all levels of biological organization, with periods ranging from milliseconds to years. Among biological rhythms, circadian clocks, of a period close to 24h, play a key role as they allow the adaptation of living organisms to the alternation of day and night. Biological rhythms represent a phenomenon of temporal self-organization in the form of sustained oscillations of the limit cycle type. Mathematical models show how the emergent property of oscillatory behavior arises from molecular interactions in cellular regulatory networks, which explains why cellular rhythms represent a major research topic in systems biology. After providing an introduction to biological rhythms and their modeling, I will focus on mathematical models for two major examples of rhythmic behavior at the cellular level : the circadian clock and the cell cycle. The coupling of these rhythms allows for their synchronization and for the occurrence of more complex patterns of oscillatory behavior. I will discuss the reasons why models for cellular rhythms tend to become more complex, upon incorporating new experimental observations. The case of cellular rhythms allows us to compare the merits of simple versus complex models for the dynamics of biological systems.

Venue: Suzuki Umetaro Hall

Broadcast:#305-2, Computational Science Research Building / SUURI-COOL (Kyoto) / 2F Seminar Room, AIMR Main Building

Event Official Language: English

​Denso IT Lab. and RIKEN Joint ​Innovation ​Seminar

June 29 (Fri) at 16:00 - 17:40, 2018

16:00-17:00 Denso IT Laboratory "About Denso IT lab." H. Iwasaki (Denso) "Human-Car interface" ​H. Tsukahara​ (Denso) ​"Math in machine leaning and computer vision" K. Ishikawa (Denso) 17:00-17:40 RIKEN "Math bridging between classical and quantum physics: quantum hall effect in classical system" T. Ozawa (RIKEN) "Di-Omega: a new particle predicted by K-computer with mathematical science" S. Gongyo (RIKEN)

Venue: Common Room #246-248

Event Official Language: Japanese

Computational Algebraic Statistics and its Applications

June 26 (Tue) at 10:00 - 16:30, 2018

Satoshi Aoki (Professor, Department of Mathematics, Kobe University)

Lecture 1 (10:00-11:30) An introduction of Groebner bases of polynomial rings Lecture 2 (13:00-14:30) Groebner bases theory in design of experiments Lecture 3 (15:00-16:30) Groebner bases theory in sampling problems of contingency tables This introductory lecture is about statistical theory from the point of view of the computational algebraic statistics, in particular the applications of Groebner bases. The statistical theory is a fundamental tool in natural science, social science and humanities, and the Groebner basis is a topic related to multi-variable polynomials. The Lecture will start from an introduction to the Groebner basis which would have wide applications in mathematics, physics, biology, chemistry, engineering, information science and computer science. Therefore, we welcome scientists in any field who are interested in this subject. The event official language is Japanese (slides and writing are in English).

Venue: #535-537, 5F, Main Research Building

Event Official Language: Japanese