Gutierrez, Julian and Harrenstein, Paul and Perelli, Giuseppe and Wooldridge, Michael - Nash Equilibrium and Bisimulation Invariance

lmcs:4791 - Logical Methods in Computer Science, September 20, 2019, Volume 15, Issue 3
Nash Equilibrium and Bisimulation Invariance

Authors: Gutierrez, Julian and Harrenstein, Paul and Perelli, Giuseppe and Wooldridge, Michael

Game theory provides a well-established framework for the analysis of concurrent and multi-agent systems. The basic idea is that concurrent processes (agents) can be understood as corresponding to players in a game; plays represent the possible computation runs of the system; and strategies define the behaviour of agents. Typically, strategies are modelled as functions from sequences of system states to player actions. Analysing a system in such a setting involves computing the set of (Nash) equilibria in the concurrent game. However, we show that, with respect to the above model of strategies (arguably, the "standard" model in the computer science literature), bisimilarity does not preserve the existence of Nash equilibria. Thus, two concurrent games which are behaviourally equivalent from a semantic perspective, and which from a logical perspective satisfy the same temporal logic formulae, may nevertheless have fundamentally different properties (solutions) from a game theoretic perspective. Our aim in this paper is to explore the issues raised by this discovery. After illustrating the issue by way of a motivating example, we present three models of strategies with respect to which the existence of Nash equilibria is preserved under bisimilarity. We use some of these models of strategies to provide new semantic foundations for logics for strategic reasoning, and investigate restricted scenarios where bisimilarity can be shown to preserve the existence of Nash equilibria with respect to the conventional model of strategies in the computer science literature.


Source : oai:arXiv.org:1808.09213
DOI : 10.23638/LMCS-15(3:32)2019
Volume: Volume 15, Issue 3
Published on: September 20, 2019
Submitted on: August 30, 2018
Keywords: Computer Science - Logic in Computer Science


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