2023/12/26 更新

オオワ タクヤ
大輪 拓也
OHWA Takuya
Scopus 論文情報  
総論文数: 0  総Citation: 0  h-index: 3

Citation Countは当該年に発表した論文の被引用数

所属
大学院工学研究院 基礎科学研究系
職名
准教授
外部リンク

研究キーワード

  • 確率論

取得学位

  • 九州大学  -  博士(数理学)   2010年03月

学内職務経歴

  • 2019年07月 - 現在   九州工業大学   大学院工学研究院   基礎科学研究系     准教授

論文

  • ANNEALING-BASED ALGORITHM FOR SOLVING CVP AND SVP 査読有り 国際誌

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

    日本オペレーションズ・リサーチ学会論文誌 ( 公益社団法人 日本オペレーションズ・リサーチ学会 )   65 ( 3 )   121 - 137   2022年07月

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    担当区分:最終著者   記述言語:英語   掲載種別:研究論文(学術雑誌)

    <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 査読有り

    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年01月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)

    The NIS-Apriori algorithm, which is extended from the Apriori algorithm, was proposed for rule generation from non-deterministic information systems and implemented in SQL. The realized system handles the concept of certainty, possibility, and three-way decisions. This paper newly focuses on such a characteristic of table data sets that there is usually a fixed decision attribute. Therefore, it is enough for us to handle itemsets with one decision attribute, and we can see that one frequent itemset defines one implication. We make use of these characteristics and reduce the unnecessary itemsets for improving the performance of execution. Some experiments by the implemented software tool in Python clarify the improved performance.

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

    Scopus

    その他リンク: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85088571315&origin=inward

  • Generation of Hints to Overcome Difficulty in Operating Interactive Recommender Systems 査読有り 国際誌

    Yuri Nakao, Takuya Ohwa, Kotaro Ohori

    RecSys Joint Workshop on Interfaces and Human Decision Making for Recommender Systems   2019年09月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)

  • Generation of hints to overcome difficulty in operating interactive recommender systems 査読有り

    Nakao Y., Ohwa T., Ohori K.

    CEUR Workshop Proceedings   2450   36 - 45   2019年01月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)

    In the field of recommendation, there have been many efforts to help users interact with recommender systems in ways that appropriately elucidate user preferences. To let users interact with recommender systems, it is desirable that recommender systems are as transparent as possible. However, it is difficult to achieve complete transparency even with a simple method for interactive recommender systems because the relationship between the item features and the user preference is not intuitive when there is a utility function to generate recommendations. We focus on multi-attribute utility theory (MAUT) as one of the simplest methods for recommender systems and clarify the difficulties with its usage in interactive environments. Then, to overcome the difficulties, we propose an algorithm to generate natural language hints to let users understand ways of operation and see more items that match their preferences. The results of an offline simulation demonstrate that our method can effectively recommend a diverse range of items to users. As future work, we will conduct empirical experiments to evaluate the performance of our method in online situations.

    Scopus

    その他リンク: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85072879340&origin=inward

  • Learning multi-way relations via tensor decomposition with neural networks 査読有り

    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年01月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)

    How can we classify multi-way data such as network traffic logs with multi-way relations between source IPs, destination IPs, and ports? Multi-way data can be represented as a tensor, and there have been several studies on classification of tensors to date. One critical issue in the classification of multi-way relations is how to extract important features for classification when objects in different multi-way data, i.e., in different tensors, are not necessarily in correspondence. In such situations, we aim to extract features that do not depend on how we allocate indices to an object such as a specific source IP; we are interested in only the structures of the multi-way relations. However, this issue has not been considered in previous studies on classification of multi-way data. We propose a novel method which can learn and classify multi-way data using neural networks. Our method leverages a novel type of tensor decomposition that utilizes a target core tensor expressing the important features whose indices are independent of those of the multi-way data. The target core tensor guides the tensor decomposition into more effective results and is optimized in a supervised manner. Our experiments on three different domains show that our method is highly accurate, especially on higher order data. It also enables us to interpret the classification results along with the matrices calculated with the novel tensor decomposition.

    Scopus

    その他リンク: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85053216047&origin=inward

  • Extracting search query patterns via the pairwise coupled topic model 査読有り

    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年02月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)

    A fundamental yet new challenge in information retrieval is the identification of patterns behind search queries. For example, the query "NY restaurant" and "boston hotel" shares the common pattern "LOCATION SERVICE". However, because of the diversity of real queries, existing approaches require data preprocessing by humans or specifying the target query domains, which hinders their applicability. We propose a probabilistic topic model that assumes that each term (e.g., "NY") has a topic (LOCATION). The key idea is that we consider topic co-occurrence in a query rather than a topic sequence, which significantly reduces computational cost yet enables us to acquire coherent topics without the preprocessing. Using two real query datasets, we demonstrate that the obtained topics are intelligible by humans, and are highly accurate in keyword prediction and query generation tasks.

    DOI: 10.1145/2835776.2835794

    Scopus

    その他リンク: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84964335710&origin=inward

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担当授業科目(学内)

  • 2022年度   確率特論

  • 2022年度   現代数学特論

  • 2022年度   統計学

  • 2022年度   統計学

  • 2022年度   解析学B

  • 2022年度   解析学B

  • 2022年度   解析学A

  • 2022年度   情報理論

  • 2021年度   確率特論

  • 2021年度   現代数学特論

  • 2021年度   微分方程式

  • 2021年度   微分方程式

  • 2021年度   複素解析学

  • 2021年度   統計学

  • 2021年度   統計学

  • 2021年度   情報理論

  • 2020年度   確率特論

  • 2020年度   微分方程式

  • 2020年度   微分方程式

  • 2020年度   統計学

  • 2020年度   情報理論

  • 2020年度   線形数学A

  • 2019年度   微分方程式

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社会貢献活動(講演会・出前講義等)

  • でたらめでいこう-確率的な手法の紹介-

    役割:講師

    九州工業大学  山口県立宇部高等学校  2021年12月09日

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    対象: 高校生

    種別:出前授業