Browsing by Author "Kamihigashi, T."

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    Organizational refinements of Nash equilibrium
    (Springer, 2021-10) Kamihigashi, T.; Keskin, K.; Sağlam, Çağrı
    Strong Nash equilibrium (see Aumann, 1959) and coalition-proof Nash equilibrium (see Bernheim et al., 1987) rely on the idea that players are allowed to form coalitions and make joint deviations. Both of these notions consider cases in which any coalition can be formed. Accordingly, there may arise “conflicts of interest” that prevent a player from choosing an action that simultaneously meets the requirements of two coalitions to which he or she belongs. Here, we address this observation by studying an organizational framework such that the coalitional structure is (i) motivated by real-life examples where players cannot form some coalitions and (ii) formulated in such a way that no conflicts of interest remain. We define an organization as an ordered collection of partitions of the player set such that any partition is coarser than the partitions that precede it. For any given organization, we introduce the notion of organizational Nash equilibrium. We analyze the existence of equilibrium in a subclass of games with strategic complementarities and illustrate how the proposed notion refines the set of Nash equilibria in some examples of normal form games
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    Robust comparative statics for non-monotone shocks in large aggregative games
    (Academic Press, 2018) Camacho, C.; Kamihigashi, T.; Sağlam, Çağrı
    A policy change that involves a redistribution of income or wealth is typically controversial, affecting some people positively but others negatively. In this paper we extend the “robust comparative statics” result for large aggregative games established by Acemoglu and Jensen (2010) to possibly controversial policy changes. In particular, we show that both the smallest and the largest equilibrium values of an aggregate variable increase in response to a policy change to which individuals' reactions may be mixed but the overall aggregate response is positive. We provide sufficient conditions for such a policy change in terms of distributional changes in parameters.