On large games with bounded essential coalition sizes

We consider games in characteristic function form where the worth of a group of players depends on the numbers of players of each of a finite number of types in the group. The games have bounded essential coalition sizes: all gains to cooperation can be achieved by coalitions bounded in absolute size (although larger coalitions are permitted they cannot realize larger per-capita gains). We show that the utility function of the corresponding "limit" market, introduced in Wooders (1988, 1994a) , is piecewise linear. The piecewise linearity is used to show that for almost all limiting ratios of percentages of player-types, as the games increase in size (numbers of players), asymptotically the games have cores containing only one payoff, and this payoff is symmetric (treats players of the same type identically). We use this result to show that for almost all limiting ratios of percentages of player-types, Shapley values of sequences of growing games converge to the unique limiting payoff.     

Anonymous price taking equilibrium in Tiebout economies with a continuum of agents: Existence and characterization

We introduce a model of a local public goods economy with a continuum of agents and jurisdictions with finite but unbounded populations, where the set of possible projects for each jurisdiction/club is unrestricted in size. Under boundedness of per capita payoffs, which simply ensures that equal treatment payoffs are bounded above, we apply results of Kaneko and Wooders (1986) to obtain nonemptiness of the core of the economy. We then demonstrate, under the stronger condition of strict small group effectiveness, that the equal treatment core coincides with the set of price-taking equilibrium outcomes with anonymous prices—that is, prices for public goods depend only on observable characteristics of agents. Existence of equilibrium follows from nonemptiness of the core and equivalence of the core to the set of equilibrium outcomes. Our approach provides a new technique for showing existence of equilibrium in economies with a continuum of agents.     

Cooperation vs. competition in R&D: The role of stability of equilibrium

We consider a model in which firms first choose process R&D expenditures and then compete in an output market. We show the symmetric equilibrium under R&D competition is sometimes unstable, in which case two asymmetric equilibria must also exist. For the latter, we find, in contrast to the literature that total profits are sometimes higher with R&D competition than with research joint venture cartelization (due to the cost asymmetry of the resulting duopoly in the noncooperative case). Furthermore, these equilibria provide another instance of R&D-induced firm heterogeneity.     

Some corrections to claims about the literature in Engl and Scotchmer (1996)

Some assertions in Engl and Scotchmer [J. Math. Econ. 26 (1996) 209] concerning prior literature are corrected. In addition, I discuss the differences between the convergence results of Engl and Scotchmer [J. Math. Econ. 26 (1996) 209], and those of this author, alone and with Martin Shubik, dating from 1980. Our prior and concurrent results show that (approximate) -cores of games with many players treat most similar players nearly equally; that is, approximate cores of large games have the equal treatment property. The convergence result of Engl and Scotchmer shows that, in per capita terms, -core payoffs to sufficiently large groups of players can be approximated by equal-treatment payoffs.     

Equilibrium play in matches: Binary Markov games

We study two-person extensive form games, or “matches,” in which the only possible outcomes (if the game terminates) are that one player or the other is declared the winner. The winner of the match is determined by the winning of points, in “point games.” We call these matches binary Markov games. We show that if a simple monotonicity condition is satisfied, then (a) it is a Nash equilibrium of the match for the players, at each point, to play a Nash equilibrium of the point game; (b) it is a minimax behavior strategy in the match for a player to play minimax in each point game; and (c) when the point games all have unique Nash equilibria, the only Nash equilibrium of the binary Markov game consists of minimax play at each point. An application to tennis is provided.