Updated on 2023/06/01

OHWA Takuya
Scopus Paper Info  
Total Paper Count: 0  Total Citation Count: 0  h-index: 3

Citation count denotes the number of citations in papers published for a particular year.

Faculty of Engineering Department of Basic Sciences
Associate Professor
External link

Research Interests

  • Probability theory


  • Kyushu University  -  Doctor of Mathematics   2010.03

Biography in Kyutech

  • 2019.07

    Kyushu Institute of Technology   Faculty of Engineering   Department of Basic Sciences   Associate Professor  



    Yamaguchi Junpei, Shimizu Toshiya, Furukawa Kazuyoshi, Ohori Ryuichi, Shimoyama Takeshi, Mandal Avradip, Montgomery Hart, Roy Arnab, Ohwa Takuya

    Journal of the Operations Research Society of Japan ( The Operations Research Society of Japan )   65 ( 3 )   121 - 137   2022.07

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    Authorship:Last author   Language:English   Publishing type:Research paper (scientific journal)

    <p>Inspired by quantum annealing, digital annealing computers specified for annealing computations have been realized on a large scale, such as the Digital Annealer (DA) developed by Fujitsu and the CMOS Annealing Machine developed by Hitachi. With the progress achieved using these computers, it has become necessary to estimate the computational hardness of cryptographic problems. This paper focuses on lattice problems, such as the closest vector problem (CVP) and shortest vector problem (SVP), which are a class of optimization problems. These problems form the basis of the security of lattice-based cryptography, which is a prime candidate for the NIST post-quantum cryptography standardization. For these lattice problems, we propose methods for generating an Ising model and solving the Ising model on annealing computers with a bit representation as the input, which represents encodings to map each integer variable in the SVP into binary variables. We propose two methods for SVPs, a basic method and a variant incorporating approximately the concept of the classical lattice enumeration. In our experimental results obtained using the second-generation DA, we succeeded in finding a shortest nonzero lattice vector in 40- and 45-dimensional lattices in the Darmstadt SVP Challenge. The basic method with a hybrid bit representation was the fastest among our methods with a bit representation, and the expected running time was estimated as 664 and 13,750 seconds for the 40- and 45-dimensional lattices, respectively. These results provide a benchmark for solving the SVP with annealing computers.</p>

    DOI: 10.15807/jorsj.65.121

    CiNii Research

  • An Adjusted Apriori Algorithm to Itemsets Defined by Tables and an Improved Rule Generator with Three-Way Decisions Reviewed

    Jian Z., Sakai H., Ohwa T., Shen K.Y., Nakata M.

    Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)   12179 LNAI   95 - 110   2020.01

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.1007/978-3-030-52705-1_7


    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85088571315&origin=inward

  • Generation of Hints to Overcome Difficulty in Operating Interactive Recommender Systems Reviewed International journal

    Yuri Nakao, Takuya Ohwa, Kotaro Ohori

    RecSys Joint Workshop on Interfaces and Human Decision Making for Recommender Systems   2019.09

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    Language:English   Publishing type:Research paper (international conference proceedings)

  • Generation of hints to overcome difficulty in operating interactive recommender systems Reviewed

    Nakao Y., Ohwa T., Ohori K.

    CEUR Workshop Proceedings   2450   36 - 45   2019.01

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    Language:English   Publishing type:Research paper (international conference proceedings)


    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85072879340&origin=inward

  • Learning multi-way relations via tensor decomposition with neural networks Reviewed

    Maruhashi K., Todoriki M., Ohwa T., Goto K., Hasegawa Y., Inakoshi H., Anai H.

    32nd AAAI Conference on Artificial Intelligence, AAAI 2018   3770 - 3777   2018.01

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    Language:English   Publishing type:Research paper (international conference proceedings)


    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85053216047&origin=inward

  • Extracting search query patterns via the pairwise coupled topic model Reviewed

    Konishi T., Ohwa T., Fujita S., Ikeda K., Hayashi K.

    WSDM 2016 - Proceedings of the 9th ACM International Conference on Web Search and Data Mining   655 - 664   2016.02

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    Language:English   Publishing type:Research paper (international conference proceedings)

    DOI: 10.1145/2835776.2835794


    Other Link: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84964335710&origin=inward

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Social activity outside the university

  • でたらめでいこう-確率的な手法の紹介-


    九州工業大学  山口県立宇部高等学校  2021.12.09

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    Audience: High school students

    Type:Visiting lecture