Akifumi Wachi# wachi.akifumi@gmail.com |  website | § GitHub | ï LinkedIn |  Google Scholar

Research Interests
My research interests lie primarily in reinforcement learning, and span the entire theory-to-application
spectrum from foundational advances all the way to deployment in real systems. I am particularly enthusiastic about conducting both empirical and theoretical studies that contribute to the improvement ofreinforcement learning, ensuring its efficacy, safety, and reliability in practical applications.

Work Experience
Chief Research Scientist

Oct 2023 - present

LY CorporationSenior Research Scientist

Sep 2022 - Sep 2023

LINE Corporation
Research Scientist

Apr 2018 - Aug 2022

IBM Research AI

Education
Mar 2021
Mar 2018
Mar 2016

Ph.D. in Computer Science at University of Tsukuba
M.S. in Aeronautics and Astronautics at University of Tokyo
B.S. in Aeronautics and Astronautics at University of Tokyo

Publications
1. Akifumi Wachi, Thien Q. Tran, Rei Sato, Takumi Tanabe, Youhei Akimoto, “Stepwise Alignment forConstrained Language Model Policy Optimizations” Neural Information Processing Systems (NeurIPS),
2024.
2. Xun Shen, Shuo Jiang, Akifumi Wachi, Kazumune Hashimoto, Sebastien Gros, “Flipping-based
Policy for Chance-Constrained Markov Decision Processes” Neural Information Processing Systems(NeurIPS), 2024.
3. Akifumi Wachi, Xun Shen, Yanan Sui, “A Survey of Constraint Formulations in Safe Reinforcement
Learning” International Joint Conference on Artificial Intelligence (IJCAI), Survey Track, 2024.
4. Akifumi Wachi, Wataru Hashimoto, Kazumune Hashimoto, “Long-term Safe Reinforcement Learningwith Binary Feedback” AAAI Conference on Artificial Intelligence (AAAI), 2024.
5. Xun Shen, Akifumi Wachi, Wataru Hashimoto, Kazumune Hashimoto, Shigemasa Takai “Safe Reinforcement Learning Using Model Predictive Control with Probabilistic Control Barrier Function”
American Control Conference (ACC), 2024.
6. Akifumi Wachi, Wataru Hashimoto, Xun Shen, Kazumune Hashimoto, “Safe Exploration in Reinforcement Learning: A Generalized Formulation and Algorithms” Neural Information Processing
Systems (NeurIPS), 2023.
7. Akifumi Wachi, Yunyue Wei, Yanan Sui, “Safe Policy Optimization with Local Generalized LinearFunction Approximations” Neural Information Processing Systems (NeurIPS), 2021.
8. Ran Iwamoto, Ryosuke Kohita, Akifumi Wachi, “Polar Embedding” The SIGNLL Conference onComputational Natural Language Learning (CoNLL), 2021.
9. Daiki Kimura, Masaki Ono, Subhajit Chaudhury, Ryosuke Kohita, Akifumi Wachi, Don Joven Agravante, Michiaki Tatsubori, Asim Munawar, Alexander Gray, “Neuro-Symbolic Reinforcement Learning with First-Order Logic” Empirical Methods in Natural Language Processing (EMNLP), Shortpaper, 2021.
10. Ryosuke Kohita, Akifumi Wachi, Daiki Kimura, Subhajit Chaudhury, Michiaki Tatsubori, Asim Munawar, “Language-based General Action Template for Reinforcement Learning Agents” Associationfor Computational Linguistics (ACL), Findings, 2021.
11. Ryosuke Kohita, Akifumi Wachi, Yang Zhao, Ryuki Tachibana, ”Q-learning with Language Modelfor Edit-based Unsupervised Summarization” Empirical Methods in Natural Language Processing(EMNLP), 2020
12. A. Wachi, Y. Sui, ”Safe Reinforcement Learning in Constrained Markov Decision Processes”, International Conference on Machine Learning (ICML), 2020
13. A. Wachi, ”Failure-Scenario Maker for Rule-based Agent using Multi-agent Adversarial Reinforcement Learning and its Application to Autonomous Driving”, International Joint Conference on Artificial Intelligence (IJCAI), 2019
14. A. Wachi, Y. Sui, Y. Yue, M. Ono, ”Safe Exploration and Optimization of Constrained MDPs using
Gaussian Processes”, AAAI Conference on Artificial Intelligence (AAAI), 201815. R. Sakagami, R. Takahashi, A. Wachi, Y. Koshiro, H. Maezawa, Y. Kasai, S. Nakasuka, ”Integral
Design Method for Simple and Small Mars Lander System Using Membrane Aeroshell”, Acta Astronautica.
16. A. Wachi, R. Takahashi, R. Sakagami, Y. Koshiro, Y. Kasai, S. Nakasuka, ”Feasibility Study forMars Landing with Small Space Probe”, AIAA SPACE and Astronautics Forum and Exposition(2017 AIAA SPACE Forum), 2017.
17. A. Wachi, ”Low-Thrust Trajectory Design to Improve Overall Mission Success Probability Incorporating Target Changes in Case of Engine Failures”, 31st International Symposium on Space Technologyand Science (ISTS), 2017. Nominated to Best Student Paper Award: First Prize (GeneralChairperson Award)
18. A. Wachi, N. Ozaki, S. Nakasuka, ”Fault-Tolerant Low-Thrust Trajectory Design with Backups forMultiple Targets”, 20th IFAC Symposium on Automatic Control in Aerospace (ACA), 2016. Nominated to the Best Student Paper Award: First Prize.

PatentsI have over 10 filed patents which can be found here:• https://patents.justia.com/search?q=akifumi+wachi

Academic Services
Conference Reviewing (Program Committee Member)• ML: NeurIPS (2021 - 2024), ICML (2021 - 2024), ICLR (2022 - 2025), AISTATS (2024 - 2025)• AI: IJCAI (2020 - 2024), AAAI (2020 - 2025)• NLP: ACL (2020 - 2023), EMNLP (2020)
Journal Reviewing• ACM Transactions on Evolutionary Learning and Optimization (Associate Editor)• IEEE Transactions on Pattern Analysis and Machine IntelligenceAwardsDean’s Award (second prize), from Faculty of Engineering, The University of Tokyo, 2018
Best Student Paper Award, First Prize (General Chairperson Award), Joint Conference: 31st ISTS,
26th ISSFD, and 8th NSAT, 2017, http://www.ists.or.jp/wp-content/uploads/2016/03/31_Prize-List.pdf
Best Student Paper Award (First Prize), IFAC Symposium on Automatic Control in Aerospace (ACA),
2016, http://aca2016.ngcaerospace.com/studentaward.php

Fellowship
Financial support to participate in Thirty-second AAAI conference on Artificial Intelligence by Society
for Promotion of Space Science (SPSS), $1.5K, February, 2018
Financial support to participate in International Astronautical Congress (IAC) by the Japan Society for
Aeronautical and Space Sciences (JSASS), $2.5K, September, 2017
Go Global Scholarships 2016 Short Study Abroad Scholarships: the University of Tokyo, $1K/month, 3months, 2016
Fellowship of the Leading Graduates Schools Program: Global Leader Program for Social Design and Management by the Ministry of Education, Culture, Sports, Science and Technology in Japan, $1K/month,
1 year, 2016
Financial support to visit California Institute of Technology (Caltech) and NASA/JPL by the Universityof Tokyo, $1.0K, February, 2014

Last updated: October 5, 2024