Fujiwara-greve, Takako

写真a

Affiliation

Faculty of Economics ( Mita )

Position

Professor

Related Websites

Remarks

FUJIWARA-GREVE, TAKAKO

External Links

Career 【 Display / hide 】

  • 1989.04
    -
    1995.03

    大学助手(経済学部)

  • 1995.04
    -
    2007.03

    大学助教授(経済学部)

  • 1995.10
    -
    1997.09

    大学経済学部学習指導副主任

  • 2001.10
    -
    2002.07

    大学国際センター学習指導主任

  • 2007.04
    -
    Present

    Professor (Dept. of Economics)

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Academic Background 【 Display / hide 】

  • 1986.03

    Keio University, Faculty of Economics

    University, Graduated

  • 1988.03

    Keio University, Graduate School, Division of Economics

    Graduate School, Completed, Master's course

  • 1995.09

    Stanford University, Graduate School of Business, Economic Analysis and Policy

    United States, Graduate School, Completed, Doctoral course

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Academic Degrees 【 Display / hide 】

  • Docter of Philosophy in Business, Stanford University, Dissertation, 1995.09

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Research Areas 【 Display / hide 】

  • Humanities & Social Sciences / Economic theory (Theoretical Economics)

  • Humanities & Social Sciences / Economic theory (Game Theory, Microeconomics)

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Research Keywords 【 Display / hide 】

  • Game Theory

  • Microeconomics

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Research Themes 【 Display / hide 】

  • Farsighted Group Formation, 

    2022.04
    -
    Present

  • Accountable Voting Systems and Economics of Rankings, 

    2018.04
    -
    Present

  • Theoretical and Experimental Research on Large Society Games, 

    2010.04
    -
    2023.03

  • Voluntary participaton of games and their application to firm reputations, 

    1999
    -
    2006

  • learning in games with bounded rationality, 

    1996
    -
    2005

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Books 【 Display / hide 】

  • A Game Theoretic Analysis of Voluntary Relationships

    Masahiro Okuno-Fujiwara, Takako Fujiwara-Greve, 勁草書房, 2025.08,  Page： 256

  • Non-Cooperative Game Theory

    Takako Fujiwara-Greve, Springer, 2015.07

  • 非協力ゲーム理論

    GREVE TAKAKO, 東京・知泉書館, 2011.05

  • Public Economics: Theory and Practice

    GREVE TAKAKO, 東洋経済新報社, 2003.04

    Scope: 113-142

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Papers 【 Display / hide 】

  • Repeated games with partner choice

    Graser C., Fujiwara-Greve T., García J., Van Veelen M.

    Plos Computational Biology 21 ( 2 )  2025.02

    ISSN  1553734X

    　View Summary

    Repetition is a classic mechanism for the evolution of cooperation. The standard way to study repeated games is to assume that there is an exogenous probability with which every interaction is repeated. If it is sufficiently likely that interactions are repeated, then reciprocity and cooperation can evolve together in repeated prisoner’s dilemmas. Who individuals interact with can however also be under their control, or at least to some degree. If we change the standard model so that it allows for individuals to terminate the interaction with their current partner, and find someone else to play their prisoner’s dilemmas with, then this limits the effectiveness of disciplining each other within the partnership, as one can always leave to escape punishment. The option to leave can however also be used to get away from someone who is not cooperating, which also has a disciplining effect. We find that the net effect of introducing the option to leave on cooperation is positive; with the option to leave, the average amount of cooperation that evolves in simulations is substantially higher than without. One of the reasons for this increase in cooperation is that partner choice creates endogenous phenotypic assortment. Compared to the standard models for the co-evolution of reciprocity and cooperation, and models of kin selection, our model thereby produces a better match with many forms of human cooperation in repeated settings. Individuals in our model end up interacting, not with random others that they cannot separate from, once matched, or with others that they are genetically related to, but with partners that they choose to stay with, and that are similarly dependable not to play defect as they are themselves.

  • Farsighted Clustering with Group-Size Effects and Reputations

    Takako Fujiwara-Greve, Toru Hokari

    Dynamic Games and Applications (Springer)  13 ( 2 ) 610 - 635 2022.09

    Research paper (scientific journal), Joint Work, Corresponding author, Accepted,  ISSN  21530785

    　View Summary

    We formulate a new model of strategic group formation by farsighted players in a seller–buyer setting. In each period, sellers are partitioned into groups/brands. At the end of each period, one seller may fail and exit the market by exogenous shock. When there is a vacant slot in the market, an entrant seller comes and chooses which existing group to join or to create a new group. There is a trade-off: larger groups enjoy more-than-proportional benefits of group size thanks to, for example, their visibility to attract customers and their negotiation power in factor markets. However, larger groups are more likely to experience member failure, which is a reputation loss. We find that when the rate of reputation loss is small, clustering is inevitable, but as the rate of reputation loss increases, the largest group with a bad reputation does not attract an entrant, dissolving a cluster. With a limited group-size benefit and a high rate of reputation loss, all entrants create a new group; that is, no clustering occurs. A mathematically interesting result is that, even though the model itself is stationary and symmetric, depending on the parameters, there may be multiple pure-strategy, symmetric stationary equilibria, or there may be no such equilibrium. The economic implications include that group reputation may prevent clustering and that similar markets can have different cluster structures.

  • Algorithms may not learn to play a unique Nash equilibrium

    Fujiwara-Greve T., Nielsen C.K.

    Journal of Computational Social Science (Journal of Computational Social Science)  4 ( 2 ) 839 - 850 2021.11

    ISSN  24322717

    　View Summary

    There is a widespread hope that, in the near future, algorithms become so sophisticated that “solutions” to most problems are found by machines. In this note, we throw some doubts on this expectation by showing the following impossibility result: given a set of finite-memory, finite-iteration algorithms, a continuum of games exist, whose unique and strict Nash equilibrium cannot be reached from a large set of initial states. A Nash equilibrium is a social solution to conflicts of interest, and hence finite algorithms should not be always relied upon for social problems. Our result also shows how to construct games to deceive a given set of algorithms to be trapped in a cycle without a Nash equilibrium.

  • "Asymmetry of Customer Loss and Recovery under Endogenous Partnerships: Theory and Evidence"

    Takako Fujiwara-Greve, Henrich R. Greve, and Stafan Jonsson

    International Economic Review 57 ( 1 ) 3 - 30 2016.02

    Research paper (scientific journal), Joint Work, Accepted

    　View Summary

    This article is inspired by real-world phenomena that firms lose customers based on imprecise information and take a long time to recover. If consumers are playing an ordinary repeated game with fixed partners, there is no clear reason why recovery happens slowly. However, if consumers are playing an endogenously repeated game, a class of simple efficient equilibria exhibits the asymmetry of fast loss and slow recovery of customers after a bad signal. Exit is systematic, but formation of a new partnership is random. We also give empirical evidence of our equilibria at an individual-firm level.

  • "Efficiency may improve when defectors exist"

    Takako Fujiwara-Greve, Masahiro Okuno-Fujiwara, and Nobue Suzuki

    Economic Theory 60 ( 3 ) 423 - 460 2015.08

    Accepted

    　View Summary

    <p>In repeated Prisoner’s Dilemma, the C-trigger strategy played by all players is well known to achieve symmetric efficiency when players are sufficiently patient. By contrast, if players are free to quit a repeated Prisoner’s Dilemma without information flow to new partners, cooperation from the outset of new partnerships cannot be a part of any symmetric equilibrium. Fujiwara-Greve and Okuno-Fujiwara (Rev Econ Stud 76:993–1021, 2009) showed that symmetric trust-building strategies can constitute an equilibrium for sufficiently long initial (D, D) (trust-building) periods. However, trust-building periods create social loss of payoffs, and there is a possibility that an asymmetric equilibrium with some players cooperating immediately, while others defect, may be more efficient. We show that there is a “fundamentally asymmetric” locally stable Nash equilibrium consisting of the most cooperative strategy (C-trigger with ending the partnership when betrayed) and the most noncooperative strategy, which plays D and ends the partnership immediately. When the deviation gain is relatively small, the fundamentally asymmetric equilibrium is neutrally stable against equilibrium entrants within trust-building strategies and is more efficient than any Nash equilibrium consisting of non-degenerate trust-building strategies. Our result indicates that behavioral diversity can be stable and beneficial for the society, even if players are free to escape from personalized punishments.</p>

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Reviews, Commentaries, etc. 【 Display / hide 】

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Presentations 【 Display / hide 】

  • Tolerance and Behavioral Diversity

    FUJIWARA-GREVE TAKAKO

    [International presentation]  SAET Meeting (Academia Sinica, Taiwan) , 

    2018.06
    , 

    Oral presentation (general), Society for the Advancement of Economic Theory

  • Tolerance and Behavioral Diversity

    FUJIWARA-GREVE TAKAKO

    [International presentation]  Dynamic Models in Economics: Workshop on Game Theory (Institute for Mathematical Sciences, National University of Singapore) , 

    2018.06
    , 

    Oral presentation (invited, special), Institute for Mathematical Sciences, National University of Singapore

  • Tolerance and Behavioral Diversity

    FUJIWARA-GREVE TAKAKO

    [International presentation]  The 2018 Arne Ryde conference and mini course on Learning, Evolution and Games (Lund University, Sweden) , 

    2018.06
    , 

    Oral presentation (invited, special), Arne Ryde Foundation

  • Exit Option Can Make Cooperation Easier

    FUJIWARA-GREVE TAKAKO

    [International presentation]  The Second Asia-Pacific Industrial Organisation Conference (APIOC 2017) (University of Auckland, New Zealand) , 

    2017.12
    , 

    Oral presentation (invited, special), ASIA-PACIFIC Industrial Organisation Society

  • Long-term Cooperation and Diverse Behavior Patterns under Voluntary Partnerships

    FUJIWARA-GREVE TAKAKO

    [International presentation]  European Meeting of the Econometric Society (ISCTE - IUL and the University of Lisbon) , 

    2017.08
    , 

    Oral presentation (general), Econometric Society

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • A Study of Collective Evaluation: Utilization of Information, Exclusion of Biases, and Promotion of Adequate Competition

    2024.04
    -
    2029.03

    基盤研究(B), Principal investigator

  • Theory and Experiment of Social Games: Voluntary Cooperation, Diverse Strategies, and International Comparison

    2017.04
    -
    2021.03

    JSPS, Grant-in-Aid for Scientific Research, Takako Fujiwara-Greve, Research grant, Principal investigator

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Awards 【 Display / hide 】

  • Graeme Woodbridge Prize

    Takako Fujiwara-Greve, Yosuke Yasuda, 2022.12, Asia-Pacific Industrial Organization Society, Inspecting Cartels over Time: With and without Leniency Program

    Type of Award： Award from international society, conference, symposium, etc.

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Courses Taught 【 Display / hide 】

  • TOPICS IN MICROECONOMICS

    2025

  • SEMINAR: MICROECONOMICS

    2025

  • SEMINAR: MATHEMATICS FOR ECONOMICS

    2025

  • SEMINAR IN SPECIAL TOPICS B

    2025

  • SEMINAR IN SPECIAL TOPICS A

    2025

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Social Activities 【 Display / hide 】

  • Associate member, Science Council of Japan

    2014.10
    -
    Present
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Memberships in Academic Societies 【 Display / hide 】

  • Game Theory Society, 

    2000.04
    -
    Present

  • American Economic Association, 

    1997.09
    -
    Present

  • Econometric Society, 

    1995.09
    -
    Present

  • Japanese Economic Association, 

    1993.07
    -
    Present
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Committee Experiences 【 Display / hide 】

  • 2024.01
    -
    Present

    Asia Regional Standing Committee Voting Member, Econometric Society

    　View Remarks

    会員による推薦の後、選挙で選ばれる。

  • 2020.06
    -
    2024.05

    監事, 日本経済学会

  • 2014.06
    -
    2016.06

    総務理事, 日本経済学会

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