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Bargaining Dynamics in Exchange Networks. Milan Vojnović Microsoft Research Joint work with Moez Draief. Allerton 2010, September 30, 2010. Nash Bargaining [ Nash ’50]. Nash Bargaining on Graphs [Kleinberg and Tardos ’08]. Nash Bargaining Solution. Stable : . Balanced : .
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Bargaining Dynamics in Exchange Networks Milan Vojnović Microsoft Research Joint work with Moez Draief Allerton 2010, September 30, 2010
Nash Bargaining Solution • Stable: • Balanced:
Step 2: Max-Min-Slack max sub. to
KT Elementary Graphs Path Cycle Blossom Bicycle
Local Dynamics • It is of interest to consider node-local dynamics for stable and balanced outcomes • Two such local dynamics: • Edge-balanced dynamics (Azar et al ’09) • Natural dynamics (Kanoria et al ’10)
Known Facts Edge-balanced dynamics • Fixed points are balanced outcomes • Convergence rate unknown
Outline • Convergence rate of edge-balanced dynamics for KT elementary graphs • A path bounding process of natural dynamics and convergence time • Conclusion
Blossom • Non-linear system:
Blossom (cont’d) path
Blossom (cont’d) Convergence time:
Bicycle • Non-linear dynamics: plus other updates as for blossom
Bicycle (cont’d) • Similar but more complicated than for a blossom
Bicycle (cont’d) Convergence time:
Quadratic convergence time in the number of matched edges, for all elementary KT graphs
Outline • Convergence rate of edge-balanced dynamics for KT elementary graphs • A path bounding process of natural dynamics and convergence time • Conclusion
The Positive Gap Condition (cont’d) • Enables decoupling for the convergence analysis