Workshop

Perspectives and applications of Koopman Operator Theory

March 19 (Thu) 9:00 - 18:00, 2026

Yoshihiko Susuki (Professor, Graduate School of Engineering, Kyoto University)
Hiroya Nakao (Professor, Department of Systems and Control Engineering, Institute of Science Tokyo)
Alexandre Mauroy (Associate Professor, Mathematics, University of Namur, Belgium)
Yuzuru Kato (Associate Professor, Department of Complex and Intelligent Systems, School of Systems Information Science, Future University-Hakodate)

PROGRAM: 9h45 - 10h15 Registration & Coffee 10h15 - 10h20 Opening Remarks - Satoshi Iso (RIKEN), Director of iTHEMS 10h20 - 11h20 SESSION 1 - Chair: Tetsuo Hatsuda (RIKEN) Yoshihiko Susuki (Kyoto University): Koopman resolvents in dynamical systems and control 11h20 -11h40 Free Discussions 11h40 - 13h00 Lunch Break & Discussions 13h00-14h00 SESSION 2 - Chair: Narumi Fujii (Institute of Science Tokyo) Alexandre Mauroy (University of Namur, Belgium): Analytic EDMD method for spectral analysis of fixed point dynamics 14h00 - 14h30 Coffee Break & Discussions 14h30 - 15h30 SESSION 3 - Chair: Tetsuo Hatsuda (RIKEN) Hiroya Nakao (Institute of Science Tokyo): Koopman operator analysis of coupled oscillator systems 15h30 - 16h00 Coffee Break & Discussions 16h00 - 17h00 SESSION 4 - Chair: Riccardo Muolo (RIKEN) Yuzuru Kato (Future University Hakodate): Analysis of quantum nonlinear oscillators on the basis of Koopman operator theory 17h00 - 17h05 Closing Remarks - Tetsuo Hatsuda, Chair of the Workshop 17h05 - 18h00 Free Discussions

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

Event Official Language: English

KEK-iTHEMS Workshop “Concepts of Quantum and Spacetime”

March 9 (Mon) - 12 (Thu) 2026

The two fundamental questions—“What is quantum?” and “What is spacetime?”—are deeply intertwined. On one hand, the formulation and interpretation of quantum theory depend both implicitly and explicitly on our conceptions of time and space. On the other hand, we believe that fully taking into account the quantum character of nature will force us to revise our understanding of spacetime. These two conceptual problems lie at the heart of the unsolved challenge of how to quantize classical spacetime, and conversely, how (semi-) classical descriptions of spacetime emerge from quantum theory. Furthermore, if the entire matter-spacetime system is a kind of quantum many-body system, thermodynamics—which governs its statistical behaviors—should play a key role in elucidating these problems. This workshop will discuss the question “How can quantum theory and spacetime be understood in a consistent manner?” from a fundamental and broad perspective. To tackle this challenge, we gather researchers in foundations of quantum theory, quantum gravity, and related fields from around the world, providing a "space and time" to share various ideas with open minds and engage in lively discussions. By exploring new concepts and principles, we hope to uncover directions to guide quantum theory over the next 100 years. This workshop covers… Foundations of quantum theory Quantum gravity and emergence of spacetime Formulation of semi-classical gravity Experimental aspects of fundamental properties in nature and quantum gravity Foundations of quantum many-body systems and thermodynamics Other related topics are welcome. We welcome short talk presentations and poster presentations. This event is a workshop jointly organized by KEK Theory Center and RIKEN iTHEMS.

Venue: Seminar Hall, Building 3, KEK

Event Official Language: English

RIKEN-Nara Women's University Joint Diversity Promotion Workshop 2026

March 2 (Mon) - 3 (Tue) 2026

The RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) and the Faculty of Science at Nara Women's University are promoting a project to foster female researchers under the auspices of the RIKEN Diversity Promotion Office. As part of the program, 21 undergraduate and graduate students from Nara Women's University will visit several laboratories on the RIKEN Wako campus to ask questions about their research and hold workshops with iTHEMS researchers. Organizers: RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) Faculty of Science, Nara Women's University March 2 (Mon) 13:15-14:15 Center for Brain Science (CBS) (C56 Ikenohata Building) Laboratory for Multi-scale Biological Psychiatry (Team Director: Akiko Hayashi-Takagi) 14:30-15:45 Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) (C01 Main Research Building, 4th Floor Rooms 435-437) Introduction to iTHEMS: Tetsuo Hatsuda (iTHEMS Division Director of Applied Mathematical Science) Lecture and Q&A: Megumi Oya (iTHEMS Medical Science Data-driven Mathematics Team Postdoctoral Researcher) 16:00-17:30 Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) (C01 Main Research Building, 4th Floor Rooms 435-437) Lecture and Q&A: Leo Spiedel (iTHEMS ECL Research Unit Leader) 18:00-20:30 Networking Session (C01, Research Main Building 3F East Side (Okochi Hall Side)) March 3 (Tue) 9:00-10:30 RIBF Facility, RIKEN Nishina Center (RNC) 11:15-12:00 Center for Quantum Computing (RQC) Optical Quantum Control Research Team (Team Director: Hidehiro Yonezawa)

Venue: RIKEN Wako Campus

Event Official Language: Japanese

RIKEN iTHEMS-Kyoto University joint workshop on Asymptotics in Astrophysics and Cosmology

March 2 (Mon) - 4 (Wed) 2026

This joint workshop will bring together physicists and mathematicians who work with asymptotics and perturbation theory techniques. This includes theorists in cosmology, high energy physics, quantum gravity, solar physics, astrophysics. Workshop overview Over three days, there will be approximately 15 invited (1 hour slot) or contributed (20-30 min slot) talks about: Fundamental asymptotics and perturbation theory techniques used in theoretical physics. Various applications of asymptotics and perturbation theory techniques in (wave transport or oscillation related) astrophysics and cosmology eigenvalue problems. The workshop will also feature hands-on Mathematica and Python tutorials introducing: Practical use of WKB methods in applied mathematics for any “Schrodinger-like” wave equations, Resummation methods in high energy theory, Deriving normal modes in stars, and their application to tidal evolution in binary star or planet systems, Eigenvalue problems in core collapse supernova theory.

Venue: 8F, Integrated Innovation Building (IIB)

Event Official Language: English

International Workshop on Quantum Geometry

February 3 (Tue) - 6 (Fri) 2026

In recent years, quantum geometry has attracted a renewed interest as an important concept in physics, and is being actively studied in a wide variety of fields ranging from condensed matter physics to high-energy physics. This international workshop aims to invite researchers actively working at the forefront of quantum geometry research and hold intensive discussions, thereby providing an opportunity to facilitate mutual interaction that will lead to future collaborations. The workshop will cover a wide range of topics related to quantum geometry, as in condensed matter physics, AMO physics, quantum gravity, quantum information, etc.

Venue: 1F, Lecture Room #112, Information Science Bldg. (C43) (Main Venue) / Satellite : 4F, "Common Space" of FQSP, Information Science Bldg.(C43)

Event Official Language: English

iTHEMS Cosmology Forum n°5 - Effective Field Theory approaches across the Universe

January 29 (Thu) 10:00 - 17:00, 2026

Katsuki Aoki (Research Assistant Professor, Yukawa Institute for Theoretical Physics, Kyoto University)
Toshifumi Noumi (Associate Professor, Graduate School of Arts and Sciences, The University of Tokyo)
Lucas Pinol (CNRS Researcher, Laboratoire de Physique de l’École Normale Supérieure (LPENS), CNRS/École Normale Supérieure, France)

This fifth workshop will bring together researchers exploring the effective field theory (EFT) framework in diverse cosmological contexts. Topics will include EFT formulations of interacting dark matter and dark energy, open EFTs for gravity, and multi-field inflationary dynamics. By highlighting recent progress and open questions, the workshop seeks to bridge insights from the early and late universe through the unifying language of EFT. In addition to the invited talks, the workshop will feature a panel discussion designed to promote interaction between the speakers and participants. One of the key goals of this event is to foster collaboration among researchers working in neighboring fields, and to encourage participation from young and early-career researchers who are interested in, but may not yet have worked on, these themes. The workshop welcomes a broad audience with an interest in theoretical cosmology, gravitation, and quantum field theory. The workshops are organised by the Cosmology Study Group at RIKEN iTHEMS.

Venue: Okochi Hall

Event Official Language: English

Mathematical Sciences Outreach Workshop 2025

November 14 (Fri) - 16 (Sun) 2025

This year's meeting on "Outreach of Mathematical Sciences" will be held from FRI NOV 14 12:30 to SUN NOV 16 15:00 as a face-to-face meeting at Institute of Mathematics for Industry of Kyushu University as "Outreach of Data Descriptive Science and Mathematical Sciences" supported by Grant-in-Aid for Transformative Research Areas (A), 2022-2026 "Establishing data descriptive science and its cross-disciplinary applications" in cooperation with RIKEN iTHEMS SUURI-COOL (Kyushu) using ZOOM for the necessary part as well.

Venue: W1-D-413, IMI Auditorium, Ito Campus, Kyushu University (Main Venue) / via Zoom

Event Official Language: Japanese

RIKEN–Berkeley Workshop on Quantum Gravity 2025

October 23 (Thu) - 24 (Fri) 2025

This workshop will serve as the first meeting of the collaboration between the Leinweber Institute for Theoretical Physics (LITP) at the University of California Berkeley and the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS). Participation is open and researchers from other institutions are welcome to attend. The workshop will feature talks on recent developments in the field of Quantum Gravity and other relevant topics.

Venue: via Zoom / #359 (23rd Morning) & #435-437 (23rd Afternoon & 24th Morning), Main Research Building

Event Official Language: English

Japan-UK Workshop on Quantum Gravity

September 22 (Mon) - 26 (Fri) 2025

The universe at extremely early times is expected to be described by some theory of quantum gravity, although we still do not know precisely what quantum gravity actually is. In modern approaches to quantum gravity, the path integral point of view provides a fundamental framework towards answering this pressing question. However, an evaluation or even just a precise definition of the path-integral for a full-fledged quantum gravity is one of the most important open problems in modern theoretical physics.

Venue: 8F, Integrated Innovation Building (IIB)

Event Official Language: English

Functional Renormalization Group at RIKEN 2025

August 25 (Mon) - 26 (Tue) 2025

Functional Renormalization Group (FRG) is a powerful theoretical framework for investigating physical systems described by field theory. Its applications span a wide range of areas, from condensed matter and statistical physics to particle physics and gravity. This two-day workshop aims to provide an overview of recent applications and developments of FRG across various fields, foster discussions on future directions, and explore opportunities for new collaborations.

Venue: #345-347, Main Research Building, RIKEN Wako Campus

Event Official Language: English

iTHEMS-NCTS Workshop

August 18 (Mon) - 21 (Thu) 2025

This workshop aims to strengthen collaboration between researchers at RIKEN iTHEMS and the National Center for Theoretical Sciences in Taiwan. It will be a four-day event, with the first two days dedicated to interdisciplinary topics. The last two days will focus on specialized areas, with one day devoted to condensed matter physics and the other to high-energy physics, including quantum gravity.

Venue: via Zoom / RIKEN Wako Campus

Event Official Language: English

Crossroads of Virology and Mathematical Sciences

August 8 (Fri) 9:30 - 17:30, 2025

Makoto Takeda (Professor, Graduate School of Medicine, The University of Tokyo)
Yasuyuki Yamaji (Professor, Graduate School of Agricultural and Life Sciences, The University of Tokyo)
Kotaro Kiga (Director, Japan Institute for Helth Security)
Daishi Fujita (Associate Professor, Kyoto University Institute for Advanced Study (KUIAS))
Miyuki Koiso (Professor Emeritus, Kyushu University)
Daisuke Kuroda (Associate Professor, Department of Biosciences, College of Humanities and Sciences, Nihon University)
Catherine Beauchemin (Deputy Director, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Shinichi Tanigawa (Associate Professor, Graduate School of Information Science and Technology, The University of Tokyo)
Takao Hashiguchi (Professor, Institute for Life And Medical Sciences, Kyoto University)
Hideo Fukuhara (Associate Professor, International Institute for Zoonosis Control, Hokkaido University)
Shohei Kojima (Special Postdoctoral Researcher, Genome Immunobiology RIKEN Hakubi Research Team, RIKEN Center for Integrative Medical Sciences (IMS))
Shuhei Miyashita (Assistant Professor, Graduate School of Agricultural Science, Tohoku University)
Ryoko Oishi-Tomiyasu (Professor, Institute of Mathematics for Industry, Kyushu University)
Suzuki Yuta (Principal Investigator, Japan Science and Technology Agency (JST))
Adnan Sljoka (Research Scientist, Molecular Informatics Team, RIKEN Center for Advanced Intelligence Project (AIP))

By creating a shared space for dialogue, we aim to stimulate new research directions and foster collaborative insights through the integration of mathematical sciences into studies of both the structural principles that govern viral form and function, and the dynamics of viral replication. We invite participation from both mathematical and theoretical scientists interested in the structure and replication mechanisms of viruses, as well as virologists who are open to exploring the potential of mathematical abstraction. Program: Morning Session I (Viruses) 10:00–10:20 Measles virus engineering Makoto Takeda (The University of Tokyo, Graduate School of Medicine) 10:20–10:40 Plant immunity to potexviruses Yasuyuki Yamaji (The University of Tokyo, Graduate School of Agricultural and Life Sciences) 10:40–11:00 Sophisticated phage infection strategies and bacterial defense responses Kotaro Kiga (National Institute of Infectious Diseases) Break (11:00–11:15) Morning Session II (Molecules, Math) 11:15–11:35 Designing Polyhedral Molecular Architectures at Will Daishi Fujita (Kyoto University, Institute for Advanced Study) 11:35–11:55 Anisotropic energy and (curved) polyhedron Miyuki Koiso (Kyushu University) 11:55–12:15 Nature-Inspired Design of Two-Component Protein Assemblies: From Cytoskeleton-Like to Virus-Like Structures Yuta Suzuki (JST PRESTO) Lunch Break (12:15–13:20) Afternoon Session I (Comp Sci, Math) 13:20–13:40 Computer-aided antibody design Daisuke Kuroda (Nihon University, Department of Life Sciences) 13:40–14:00 Revealing Protein Allostery and Functional Dynamics via Rigidity Theory and NMR Adnan Sljoka（RIKEN AIP） 14:00–14:20 Using mathematical models to identify experimental pitfalls when probing virus replication in vitro Catherine Beauchemin (RIKEN iTHEMS) 14:20–14:40 Combinatorics behind statics and flexibility of graphs Shinichi Tanigawa (The University of Tokyo, Graduate School of Information Science and Technology) Break (14:40–14:55) Afternoon Session II (Structures) 14:55–15:15 Glycoprotein structures in human pathogenic RNA viruses Takao Hashiguchi (Kyoto University, Graduate School of Medicine and Biomedical Sciences) 15:15–15:35 Introduction of cryo-electron microscopy facilities at Hokkaido University Hideo Fukuhara (Hokkaido University, Research Center for Zoonosis Control) Break (15:35–15:50) Afternoon Session III (Viruses, Math) 15:50–16:10 Human genetics during virus infection Shohei Kojima (Keio University, Bio2Q) 16:10–16:30 Suicidal population resistance of land plants against viruses Shuhei Miyashita (Tohoku University, Graduate School of Agricultural Science) 16:30–16:50 Mathematical and crystallographic perspectives in virology Ryoko Tomiyasu (Kyushu University, IMI) Organizers: Catherine Beauchemin (RIKEN iTHEMS) Makoto Takeda (University of Tokyo, Graduate School of Medicine) Ryoko Tomiyasu (Kyushu University, IMI)

Venue: #359, 3F, Main Research Building (Main Venue) / via Zoom

iTHEMS Cosmology Forum #4 - Evolving Cosmos: new physical insights from new spectroscopic data

August 4 (Mon) - 5 (Tue) 2025

Seshadri Nadathur (Associate Professor, University of Portsmouth, UK)
Andrei Cuceu (NASA Einstein Fellow, Lawrence Berkeley National Laboratory (LBNL), USA)
Gerrit Farren (Postdoc, Lawrence Berkeley National Laboratory (LBNL), USA)
Antonio De Felice (Associate Professor, Yukawa Institute for Theoretical Physics, Kyoto University)
Linda Blot (Project Assistant Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo)
Wen Yin (Associate Professor, Department of Physics, Graduate School of Science, Tokyo Metropolitan University)

iTHEMS Cosmology Forum Workshop is a series of short workshops, each focusing on an emerging topics in cosmology. The target audience is cosmologists, high-energy physicists and astronomers interested in learning about the subject, not just those who have already worked on the topic. The goal of the workshop is to provide working knowledge of the topic and leave dedicated time for discussions to encourage mutual interactions among participants. The fourth workshop is dedicated to new physics discoveries enabled by new spectroscopic data. Nearly three decades after the discovery of accelerated expansion, there is at last compelling data pointing away from the simple cosmological constant. The results of new data hint at evolving dark energy, but the statistical significance and physical interpretation are both far from clear. Furthermore, another anticipated new physics measurement of the neutrino mass has also proven difficult. With this workshop, we aim to interrogate both the statistical evidence for new physics as well as the theoretical implications if these new results are confirmed. This forum will consist of two days. The workshop will be in English. The workshops are organised by the iTHEMS Cosmology Forum working group, which is the successor of the Dark Matter Working Group at RIKEN iTHEMS. Important dates: July 18 - Registration deadline August 4th, 5th - Workshop Days Invited Speakers: Sesh Nadathur (University of Portsmouth) Andrei Cuceu (LBNL) Gerrit Farren (LBNL) Antonio De Felice (YITP) Linda Blot (IPMU) Wen Yin (TMU)

Venue: #435-437, 4F, Main Research Building

Event Official Language: English

The Theory of Periodic Tangles & Their Interdisciplinary Applications

July 28 (Mon) - August 1 (Fri) 2025

The mathematical characterization of entanglement holds immense potential for describing the mechanical functions of diverse physical systems and materials. A universal interdisciplinary study, involving scientists, engineers, and artists promises both advance of the field itself and significant contribution to the research and design of innovative solutions for textiles, medical devices, polymers, molecular chemistry, or construction materials among others. The program seeks an alternative to the trial–and–error approach, bringing together academia and industry to seek new sustainable solutions and inspiration, contributing to society. It will consist not only of scientific exchanges but will promote cultural impact by organizing exhibitions or hands–on workshops. Additionally, it will encourage several discussions by providing networking opportunities and utilizing the unique venue of House of Creativity at Tohoku University. This workshop will gather researchers from various disciplines and include invited lectures, a poster session, roundtable discussions, and brainstorming activities. Our focus will be on exploring the connections between knot theory and its applications in areas such as polymers and soft matter, textile mechanics, graphic design, and more. This event includes a joint symposium between the WPI–AIMR (Tohoku University) and WPI–SKCM2 (Hiroshima University) on Friday, August 1st, 2025: INTERWOVEN: A WPI–AIMR & WPI–SKCM2 Symposium, Towards a Universal Topological Model of Entangled Structures for Sustainable Metamaterials Please fill in the registration form by June 16th 2025. Confirmed speakers (alphabetical order): Jörn Dunkel (Massachusetts Institute of Technology) Yuanyuan Guo (Tohoku University) Tatsuki Hayama (Keio University) Louis H. Kauffman (University of Illinois at Chicago) Yuka Kotorii (Hiroshima University) Sofia Lambropoulou (National Technical University of Athens) Eleni Panagiotou (Arizona State University) Pedro M. Reis (École Polytechnique Fédérale de Lausanne) Takahiro Sakaue (Aoyama Gakuin University) Vanessa Sanchez (Rice University) Henry Segerman (Oklahoma State University) Koya Shimokawa (Ochanomizu University) Hiroshi Suito (Tohoku University) Ryuichi Tarumi (Osaka University) Hirofumi Wada (Ritsumeikan University) Please refer to the workshop website via the relevant link for more details. We are looking forward to your participation and to welcoming you to Sendai!

Venue: TOKYO ELECTRON House of Creativity, Katahira Campus, Tohoku University

Event Official Language: English

Recent Developments and Challenges in Tensor Networks: Algorithms, Applications to science, and Rigorous theories

July 28 (Mon) - August 8 (Fri) 2025

Venue: Panasonic Hall, Yukawa Institute for Theoretical Physics, Kyoto University

Event Official Language: English

iTHEMS-TheoryCenter(KEK) Scientific Writing and DEI Workshop

June 24 (Tue) - 25 (Wed) 2025

Ashleigh Griffin (Professor, Department of Biology, University of Oxford, UK)
Stuart West (Professor, Department of Biology, University of Oxford, UK)
Ryosuke Iritani (Senior Research Scientist, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

This is a two-day KEK-iTHEMS workshop on scientific writing and diversity, equity, and inclusion. For more details, please visit the workshop website via the relevant link.

Venue: 2F Large Conference Room, Administrative Headquarters, RIKEN Wako Campus

Event Official Language: English

Mini-Workshop on Neuro Science

May 16 (Fri) 9:00 - 12:00, 2025

Satoshi Iso (Director, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Takuya Isomura (Unit Leader, Brain Intelligence Theory Unit, RIKEN Center for Brain Science (CBS))
Taro Toyoizumi (Team Director, Laboratory for Neural Computation and Adaptation, RIKEN Center for Brain Science (CBS))
Kazuo Okanoya (Professor, Advanced Comprehensive Research Organization (ACRO), Teikyo University)
Atsushi Iriki (Specially Appointed Professor, Advanced Comprehensive Research Organization, Teikyo University)
Gary Shiu (Professor, Department of Physics, University of Wisconsin-Madison, USA)

[Program] 9:00am – 9:05am Satoshi Iso (iTHEMS RIKEN) “Opening Remarks” 9:05am – 9:35am Takuya Isomura (CBS RIKEN) “Triple equivalence integrates neural network dynamics, statistical inference, and computation” 9:45m – 10:15am Taro Toyoizumi (CBS RIKEN) “Chaotic neural dynamics facilitate probabilistic computations through sampling” 10:25am – 10:55am Kazuo Okanoya (Teikyo University) “Brain topography and auditory processing in birds and rats” 11:05am – 11:30am Atsushi Iriki (Teikyo University, iTHEMS RIKEN) “From Classical to Quantum: Rethinking Science, Consciousness, and Civilization” 11:30am – Gary Shiu (University of Wisconsin) “Summary: Mathematical Science and Brain” Followed by a seminar 2:00pm – 3:30pm Prof. Gary Shiu (University of Wisconsin) Topology and Brain Science Room 359, 3rd floor, Main Research Building, RIKEN

Venue: #345-347, Main Research Building, RIKEN Wako Campus (Main Venue) / via Zoom

Event Official Language: English

From Quarks to Neutron Stars: Insights from kHz gravitational waves

April 23 (Wed) - 24 (Thu) 2025

Astronomical observations of binary neutron star mergers and supernovae provide unique opportunities to explore physics spanning from quarks to neutron stars. The groundbreaking multi-messenger observation of GW170817, combining electromagnetic signals and gravitational waves, vividly demonstrated this potential. Furthermore, if a core-collapse supernova were to occur in our galaxy, it would likely become the first event where electromagnetic signals, neutrinos, and gravitational waves are detected together. The interior of neutron stars is not yet well understood due to their extreme density, where exotic states of matter may emerge. Gravitational waves, particularly in the kilohertz band, play a crucial role in extracting information about such ultra-high densities. In recent years, several concepts for kilohertz-band gravitational wave detectors, such as Australia's NEMO, have been proposed to advance multi-messenger studies of high density astrophysical objects. KAGRA in Japan is also exploring upgrades aimed at enhancing high-frequency sensitivity, which could significantly improve sky localization accuracy and enable the detection of post-merger signals. This workshop aims to explore the transformative potential of high-frequency gravitational wave observations for multi-messenger astrophysics, with a focus on their implications for nuclear and neutron star physics. The workshop aims to spark dynamic discussions and cultivate new collaborations among participants through invited talks by leading experts and engaging poster presentations.

Venue: via Zoom

Event Official Language: English