Updated on 2025/06/09

Information

 

写真a

 
SUN ZHAOHONG
 
Organization
Faculty of Information Science and Electrical Engineering Department of Informatics Associate Professor
Joint Graduate School of Mathematics for Innovation (Concurrent)
School of Engineering Department of Electrical Engineering and Computer Science(Concurrent)
Graduate School of Information Science and Electrical Engineering Department of Information Science and Technology(Concurrent)
Title
Associate Professor
External link

Research Areas

  • Informatics / Intelligent informatics

Degree

  • The University of New South Wales

Research Interests・Research Keywords

  • Research theme: Matching Theory and its Applications

    Keyword: Artificial Intelligence, Computational Economics, Algorithmic Game Theory, Matching Theory

    Research period: 2016.5 - Present

Papers

  • Achieving Balanced Representation in School Choice with Diversity Goals. Reviewed

    Zhaohong Sun, Makoto Yokoo

    The 39th Annual AAAI Conference on Artificial Intelligence   14129 - 14138   2025.4

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

  • Multi-rank smart reserves: A general framework for selection and matching diversity goals Reviewed International coauthorship

    Aziz, H; Sun, ZH

    ARTIFICIAL INTELLIGENCE   339   104274   2025.2   ISSN:0004-3702 eISSN:1872-7921

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Artificial Intelligence  

    We study a problem where each school has flexible multi-ranked diversity goals, and each student may belong to multiple overlapping types, and consumes only one of the positions reserved for their types. We propose a novel choice function for a school to select students and show that it is the unique rule that satisfies three fundamental properties: maximal diversity, non-wastefulness, and justified envy-freeness. We provide a fast polynomial-time algorithm for our choice function that is based on the Dulmage Mendelsohn Decomposition Theorem as well as new insights into the combinatorial structure of constrained rank maximal matchings. Even for the case of minimum and maximum quotas for types (that capture two ranks), ours is the first known polynomial-time approach to compute an optimally diverse choice outcome. Finally, we prove that the choice function we design for schools, satisfies substitutability and hence can be directly embedded in the generalized deferred acceptance algorithm to achieve strategyproofness and stability. Our algorithms and results have immediate policy implications and directly apply to a variety of scenarios, such as where hiring positions or scarce medical resources need to be allocated while taking into account diversity concerns or ethical principles.

    DOI: 10.1016/j.artint.2024.104274

    Web of Science

    Scopus

  • A Fair and Optimal Approach to Sequential Healthcare Rationing Reviewed

    Zhaohong Sun

    The Twenty-Sixth ACM Conference on Economics and Computation   2025

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

  • Probabilistic Analysis of Stable Matching in Large Markets with Siblings. Reviewed

    Zhaohong Sun, Tomohiko Yokoyama, Makoto Yokoo.

    the 34th International Joint Conference on Artificial Intelligence   2025

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

  • Stable Matchings in Practice: A Constraint Programming Approach

    Sun Z., Yamada N., Takenami Y., Moriwaki D., Yokoo M.

    Proceedings of the AAAI Conference on Artificial Intelligence   38 ( 20 )   22377 - 22384   2024.3   ISSN:21595399

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    Publisher:Proceedings of the AAAI Conference on Artificial Intelligence  

    We study a practical two-sided matching problem of allocating children to daycare centers, which has significant social implications. We are cooperating with several municipalities in Japan and our goal is to devise a reliable and trustworthy clearing algorithm to deal with the problem. In this paper, we describe the design of our new algorithm that minimizes the number of unmatched children while ensuring stability. We evaluate our algorithm using real-life data sets, and experimental results demonstrate that our algorithm surpasses the commercial software that currently dominates the market in terms of both the number of matched children and the number of blocking coalitions (measuring stability). Our findings have been reported to local governments, and some are considering adopting our proposed algorithm in the near future, instead of the existing solution. Moreover, our model and algorithm have broader applicability to other important matching markets, such as hospital-doctor matching with couples and school choice with siblings.

    DOI: 10.1609/aaai.v38i20.30244

    Scopus

  • Stable Matchings in Practice: A Constraint Programming Approach. Reviewed International journal

    Zhaohong Sun, @Naoyuki Yamada, @Yoshihiro Takenami, @Daisuke Moriwaki, Makoto Yokoo.

    The 38th Annual AAAI Conference on Artificial Intelligence   2024.2

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    Language:English   Publishing type:Research paper (scientific journal)  

  • Daycare Matching in Japan: Transfers and Siblings. Reviewed International journal

    Zhaohong Sun, @Daisuke Moriwaki, @Yoshihiro Takenami, @Yoji Tomita, Makoto Yokoo.

    Thirty-Seventh AAAI Conference on Artificial Intelligence   2023.2

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    Language:English   Publishing type:Research paper (scientific journal)  

  • Fairness Concepts for Indivisible Items with Externalities. Invited Reviewed International journal

    @Haris Aziz, @Warut Suksompong, Zhaohong Sun, @Toby Walsh.

    Thirty-Seventh AAAI Conference on Artificial Intelligence   2023.2

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    Language:English   Publishing type:Research paper (scientific journal)  

  • Weighted Envy-free Allocation with Subsidy. Reviewed International coauthorship

    Haris Aziz, Xin Huang, Kei Kimura, Indrajit Saha, Zhaohong Sun, Mashbat Suzuki, Makoto Yokoo

    The 24th International Conference on Autonomous Agents and Multiagent Systems   2025

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

  • New Concept of Fairness Applicable to School Choice

    WAKASUGI Temma, KIMURA Kei, SUN Zhaohong, YOKOO Makoto

    Proceedings of the Annual Conference of JSAI   JSAI2024 ( 0 )   2F6GS501 - 2F6GS501   2024   eISSN:27587347

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    Language:Japanese   Publisher:The Japanese Society for Artificial Intelligence  

    <p>The theory of two-sided matching has been extensively developed, and it is hoped that matching will reduce students' envies and improve overall welfare. However, it turns out that there exists a trade-off between efficiency and fairness. Therefore, keeping fairness at a certain level that can be applied in the real world also leads to increased efficiency. Our contribution is to establish a weaker fairness requirement called reverse Envy-Freeness from up to k peers (r-EF-k). r-EF-k requires that each student is envied by at most k students. By varying k, r-EF-k can represent different levels of fairness. We discuss mechanism that satisfy r-EF-k and certain efficiency properties.</p>

    DOI: 10.11517/pjsai.jsai2024.0_2f6gs501

    CiNii Research

  • Fairness and Efficiency Trade-off in Two-Sided Matching

    Cho S.H., Kimura K., Liu K., Liu K.G., Liu Z., Sun Z., Yahiro K., Yokoo M.

    Proceedings of the International Joint Conference on Autonomous Agents and Multiagent Systems, AAMAS   2024-May   372 - 380   2024   ISSN:15488403

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    Publisher:Proceedings of the International Joint Conference on Autonomous Agents and Multiagent Systems, AAMAS  

    The theory of two-sided matching has been extensively developed and applied to many real-life application domains. As the theory has been applied to increasingly diverse types of environments, researchers and practitioners have encountered various forms of distributional constraints. As a mechanism can handle a more general class of constraints, we can assign students more flexibly to colleges to increase students' welfare. However, it turns out that there exists a trade-off between students' welfare (efficiency) and fairness (which means no student has justified envy). Furthermore, this trade-off becomes sharper as the class of constraints becomes more general. The first contribution of this paper is to clarify the boundary on whether a strategyproof and fair mechanism can satisfy certain efficiency properties for each class of constraints. Our second contribution is to establish a weaker fairness requirement called envy-freeness up to k peers (EF-k), which is inspired by a similar concept used in the fair division of indivisible items. EF-k guarantees that each student has justified envy towards at most k students. By varying k, EF-k can represent different levels of fairness. We investigate theoretical properties associated with EF-k. Furthermore, we develop two contrasting strategyproof mechanisms that work for general hereditary constraints, i.e., one mechanism can guarantee a strong efficiency requirement, while the other can guarantee EF-k for any fixed k. We evaluate the performance of these mechanisms through computer simulation.

    Scopus

  • Fairness and Nonwastefulness in Two-Period Matching

    KOMETANI Hayato, KIMURA Kei, SUN Zhaohong, YOKOO Makoto

    Proceedings of the Annual Conference of JSAI   JSAI2024 ( 0 )   1I3GS501 - 1I3GS501   2024   eISSN:27587347

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    Language:Japanese   Publisher:The Japanese Society for Artificial Intelligence  

    <p>In this paper, we explore a two-period matching problem in which agents' preferences may evolve over time. This model enables agents to be matched with different partners over the two periods. Previous research defines dynamic stability as the absence of any single agent or pair of agents gaining an advantage through coalition across any period. We introduce new fairness, nonwastefulness and individually rationality notions tailored for the two-period matching setting and examine its relationship with dynamic stability. We also discuss the existence of matching that simultaneously satisfies the newly introduced fairness and nonwastefulness properties.</p>

    DOI: 10.11517/pjsai.jsai2024.0_1i3gs501

    CiNii Research

  • Daycare Matching in Japan: Transfers and Siblings

    Sun Z., Takenami Y., Moriwaki D., Tomita Y., Yokoo M.

    Proceedings of the 37th AAAI Conference on Artificial Intelligence, AAAI 2023   37   14487 - 14495   2023.6   ISBN:9781577358800

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    Publisher:Proceedings of the 37th AAAI Conference on Artificial Intelligence, AAAI 2023  

    In this paper, we study a daycare matching problem in Japan and report the design and implementation of a new centralized algorithm. There are two features that make this market different from the classical hospital-doctor matching problem: i) some children are initially enrolled and prefer to be transferred to other daycare centers; ii) one family may be associated with two or more children and is allowed to submit preferences over combinations of daycare centers. We revisit some well-studied properties including individual rationality, non-wastefulness, as well as stability, and generalize them to this new setting. We design an algorithm based on integer programming (IP) that captures these properties and conduct experiments on five real-life data sets provided by three municipalities. Experimental results show that i) our algorithm performs at least as well as currently used methods in terms of numbers of matched children and blocking coalition; ii) we can find a stable outcome for all instances, although the existence of such an outcome is not guaranteed in theory.

    DOI: 10.1609/aaai.v37i12.26694

    Scopus

  • Fairness Concepts for Indivisible Items with Externalities

    Aziz H., Suksompong W., Sun Z., Walsh T.

    Proceedings of the 37th AAAI Conference on Artificial Intelligence, AAAI 2023   37   5472 - 5480   2023.6   ISBN:9781577358800

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    Publisher:Proceedings of the 37th AAAI Conference on Artificial Intelligence, AAAI 2023  

    We study a fair allocation problem of indivisible items under additive externalities in which each agent also receives utility from items that are assigned to other agents. This allows us to capture scenarios in which agents benefit from or compete against one another. We extend the well-studied properties of envy-freeness up to one item (EF1) and envy-freeness up to any item (EFX) to this setting, and we propose a new fairness concept called general fair share (GFS), which applies to a more general public decision making model. We undertake a detailed study and present algorithms for finding fair allocations.

    DOI: 10.1609/aaai.v37i5.25680

    Scopus

  • Matching Algorithms under Diversity-Based Reservations

    Aziz H., Chu S.M., Sun Z.

    Proceedings of the International Joint Conference on Autonomous Agents and Multiagent Systems, AAMAS   2023-May   2469 - 2471   2023   ISSN:15488403

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    Publisher:Proceedings of the International Joint Conference on Autonomous Agents and Multiagent Systems, AAMAS  

    Selection under category or diversity constraints is a ubiquitous and widely-applicable problem that is encountered in immigration, school choice, hiring, and healthcare rationing. These diversity constraints are typically represented by minimum and maximum quotas on various categories or types. We undertake a detailed comparative study of applicant selection algorithms with respect to the diversity goals.

    Scopus

  • Fair Pairwise Exchange among Groups. Invited Reviewed International journal

    Zhaohong Sun, Taiki Todo, Toby Walsh.

    International Joint Conference on Artificial Intelligence   2021.8

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    Language:English  

  • School Choice with Flexible Diversity Goals and Specialized Seats. Reviewed International journal

    Haris Aziz, Zhaohong Sun

    International Joint Conferences on Artificial Intelligence   2021.8

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    Language:English  

  • New Algorithms for Japanese Residency Matching. Invited Reviewed International journal

    Zhaohong Sun, Taiki Todo, Makoto Yokoo.

    International Joint Conferences on Artificial Intelligence   2021.8

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    Language:English  

  • Multi-Rank Smart Reserves. Reviewed International journal

    Haris Aziz, Zhaohong Sun

    ACM Conference on Economics and Computation   2021.7

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    Language:English  

  • Mechanism Design for School Choice with Soft Diversity Constraints. Reviewed International journal

    Haris Aziz, Serge Gaspers, Zhaohong Sun

    International Joint Conferences on Artificial Intelligence   2021.1

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    Language:English  

  • Mechanism Design for School Choice with Soft Diversity Constraints. Reviewed International journal

    Haris Aziz, Serge Gaspers, Zhaohong Sun

    International Conference on Autonomous Agents and Multiagent Systems   2020.5

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    Language:English  

  • Multiple Levels of Importance in Matching with Distributional Constraints. Reviewed International journal

    Haris Aziz, Serge Gaspers, Zhaohong Sun, Makoto Yokoo

    International Conference on Autonomous Agents and Multiagent Systems   2020.5

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    Language:English  

  • New Challenges in Matching with Constraints. Reviewed International journal

    Zhaohong Sun

    International Conference on Autonomous Agents and Multiagent Systems   2020.5

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    Language:English  

▼display all

Presentations

  • Probabilistic Analysis of Stable Matching in Large Markets with Siblings. International conference

    Zhaohong Sun

    the 34th International Joint Conference on Artificial Intelligence 

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    Event date: 2025.8

    Language:English   Presentation type:Oral presentation (general)  

  • A Fair and Optimal Approach to Sequential Healthcare Rationing International conference

    Zhaohong Sun

    The Twenty-Sixth ACM Conference on Economics and Computation 

     More details

    Event date: 2025.7

    Language:English   Presentation type:Oral presentation (general)  

  • Achieving Balanced Representation in School Choice with Diversity Goals. International conference

    Zhaohong Sun

    The 39th Annual AAAI Conference on Artificial Intelligence  2025.2 

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    Event date: 2025.2 - 2025.3

    Language:English   Presentation type:Poster presentation  

  • Stable Matchings in Practice: A Constraint Programming Approach. International conference

    Zhaohong Sun

    The 38th Annual AAAI Conference on Artificial Intelligence  2024.2 

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    Event date: 2024.2

    Language:English   Presentation type:Oral presentation (general)  

    Venue:VANCOUVER   Country:Canada  

Research Projects

Class subject

  • ゲーム理論

    2024.4 - 2024.9   First semester

  • 国際科学特論Ⅱ

    2023.10 - 2024.3   Second semester

  • 数学共創概論Ⅰ

    2023.4 - 2023.9   First semester

Outline of Social Contribution and International Cooperation activities

  • 国際大会のプログラム委員会:AAAI-24、AAMAS-24、EC-24、GAIW-24、IJCAI-24、AAAI-23、IJCAI-23、AAAI-22、IJCAI-22、GAIW-22、IJCAI-21