Privacy-aware Nash Equilibrium Synthesis with Partially Ordered LTLObjectives

Caleb Probine, Abhishek Ninad Kulkarni, Ufuk Topcu

Abstract: Nash equilibrium is a fundamental solution concept for modeling the behavior of self-interested agents. We develop an algorithm to synthesize pure Nash equilibria in two-player deterministic games on graphs where players have partial preferences over objectives expressed with linear temporal logic over finite traces. Previous approaches for Nash equilibrium synthesis assume that players' preferences are common knowledge. Instead, we allow players' preferences to remain private but enable communication between players. The algorithm we design synthesizes Nash equilibria for a complete-information game, but synthesizes these equilibria in an incomplete-information setting where players' preferences are private. The algorithm is privacy-aware, as instead of requiring that players share private preferences, the algorithm reduces the information sharing to a query interface. Through this interface, players exchange information about states in the game from which they can enforce a more desirable outcome. We prove the algorithm's completeness by showing that it either returns an equilibrium or certifies that one does not exist. We then demonstrate, via numerical examples, the existence of games where the queries the players exchange are insufficient to reconstruct players' preferences, highlighting the privacy-aware nature of the algorithm we propose.