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Iterated Prisoner’s Dilemma on Alliance Network. Tomoki Furukawazono* Yusuke Takada** Takashi Iba ** *Graduate School of Media and Governance, Keio University **Faculty of Policy Management, Keio University. - PowerPoint PPT Presentation
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Iba Laboratory
Iterated Prisoner’s Dilemmaon Alliance Network
Tomoki Furukawazono*Yusuke Takada**
Takashi Iba** *Graduate School of Media and Governance, Keio University
**Faculty of Policy Management, Keio University
Iba Laboratory
Social System Analysis with the concept of “Complex System” and “Autopoietic System”
• Complex System– Society as the swarm / group of
agents and its interactions.
• Autopoietic System– Society as the nexus of
“communication”– The difference between Social
System / Social Structure– Proposed by Niklas Luhmann
Iba Laboratory
Understanding the social systems through modeling and simulation
Iba Laboratory
“PlatBox” as a new tools for thinking• PlatBox Simulator
– a software platform to execute and to analyze the agent-based social simulations.
• Component Builder– The tool for designing the model
component plugged into PlatBox Simulator.
– The modeler can develop his/her simulation program just by drawing model diagrams in the modeling language (UML).
Iba Laboratory
“PlatBox” as a new tools for thinking• Multi-Agent simulation on Social Network of agents
• Dynamics on the social network• Dynamics of the social network
Iba LaboratoryAlliance Network
NATO
Japan-U.S. Alliance
Nation Node,⇒ Alliance Edge⇒
Alliance can be considered as network
will examine how the cooperation within nations emerges in the alliances and helps create a stable network.
This research,
①
Iba Laboratory
②Alliance Dilemma (Snyder 1984)
It is ideal for allies to give full support for each other e.g.) Franco-Russian Alliance (1892-1917)
Most cases end up in a dilemma e.g.) Japan-US Alliance
Abandoning allies creates a chance to attack for others.
From this payoff matrix, Alliance Dilemma = Prisoner’s Dilemma
Iba Laboratory
ExperimentTo see the difficulty of maintaining the alliance
Alliance forms a network
+Alliance Dilemma = Prisoner’s Dilemma
⇒ Iterated Prisoner’s Dilemma game will be played on the Alliance Network
Iba Laboratory
The Simulation Model
①Dilemma Game
Px points
P y points
②Strategy Change
P yPx >P yPx <IF
Change strategy with this percentage
Maintain its strategy
Repeat this process
Based on Santos and Pacheco (2005)
Payoff depending on its own strategy
Iba Laboratory
Parameter
●Percentage of initial cooperators : 50%●Payoff for free riders( b ) : 1~2●Evaluation Year : 1952~2000
●Steps :2100●Alliance Data from Correlates of War http://cow2.la.psu.edu/
Iba Laboratory
Simulation Results
Fraction of
cooperators
Shows the great influence of the free-riders in an Alliance Network
The results show high fraction of cooperators in the years 1964-1976 WHY??
Iba Laboratory
step0
step1step2
Betrayer increases but U.K. and France stay cooperative
YEAR1976
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Betrayer decreases due to U.K. and France
step31 step32 step33
Iba Laboratory
Analysis of Inner Mechanism
Fraction of cooperators
steps
Nations with its own multilateral alliances works to maintain the cooperation
Iba Laboratory
Conclusion & Consideration
In the Alliance network that Japan belonged to after WWII,
The betrayal in the alliance causes a great effect not only within the alliance but to the whole network
For the Alliance network, the existence of multilateral alliance, such as of French or British, helps to maintain the cooperation within the alliance network
Iba Laboratory
thank you very mucharigato!