Exit equilibrium: Towards understanding voluntary participation in security games
Parinaz Naghizadeh, Mingyan Liu · 2016
In a system of interdependent users, the security of an entity is affected not only by that user's effort towards securing her system, but also by the security decisions of other users. The provision of security in such environment is modeled as a public good provision problem, and is referred to as a security game. In this paper, we propose the notion of exit equilibrium to study users' voluntary participation in mechanisms for provision of non-excludable public goods. We show the fundamental result that, due to the non-excludable nature of security, there exists no reliable mechanism which can incentivize the socially optimal investment profile, while ensuring voluntary participation and maintaining a weakly balanced budget, for all instances of security games. To better understand the features of the games that lead to this result, we consider the class of weighted effort games, and apply the two well-known Pivotal (VCG) and Externality mechanisms. Through analysis and simulation, we identify the effects of several features of the problem environment, including diversity in user types, multiplicity of exit equilibria, and users' self-dependence levels, on the performance of these mechanisms.