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Applications of Category Theory to Games and Economic Behavior

Research Project

Project/Area Number 17K18553
Research Category

Grant-in-Aid for Challenging Research (Exploratory)

Allocation TypeMulti-year Fund
Research Field Economics, Business Administration, and related fields
Research InstitutionUniversity of Tsukuba

Principal Investigator

Turnbull Stephen John  筑波大学, システム情報系, 准教授 (90240621)

Project Period (FY) 2017-06-30 – 2020-03-31
Project Status Completed (Fiscal Year 2019)
Budget Amount *help
¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
Fiscal Year 2019: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Keywords圏論 / ゲーム圏 / モナド / 混合延長 / category theory / game category / monad / mixed extension / ゲーム理論 / ゲーム分類 / game theory / comparison theorems
Outline of Final Research Achievements

Game theory is a branch of mathematics useful in understanding strategic behavior in society, especially economic behavior. Category theory is a set of tools for analyzing and comparing mathematical structures, and for translating from one kind of structure to another.
In this exploratory research, we first define two categories of noncooperative games in strategic form. We use these categories to examine the structure of such games, showing in both categories that when the functor extending a game to its mixed extension is paired with its right adjoint forgetful functor (the process of treating the extended game as a game, without using the fact that its strategies are probability distributions), the forgetful functor is monadic. We show that category-theoretic isomorphism classes reproduce the traditional classification of 2x2 matrix games.

Academic Significance and Societal Importance of the Research Achievements

混合延長関手の忘却関手はモナディックという定理の異義とは混合延長ゲームが戦略が確率分布で報酬関数が線形型である特別ゲームの種類でありながらすべてのゲームの行動をモデル化できることを証明する。重要点は社会現象をモデル化する一般のゲームに均衡が存在しない場合があるが、そのゲームの混合延長には均衡が存在する。
ランダム行動の解釈が困難の場合があるが、解釈が明らかの場合もある。だが、均衡のないゲームには解釈がないのでゲームその混合延長の関係の理解を深めることが大きな貢献と考えられる。

Report

(4 results)
  • 2019 Annual Research Report   Final Research Report ( PDF )
  • 2018 Research-status Report
  • 2017 Research-status Report

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Published: 2017-07-21   Modified: 2021-02-19  

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