Alexander Matros

Contests with a stochastic number of players

We study Tullocks (1980) n-player contest when each player has an independent probability 0 2 individual equilibrium spending as a function of p is single-peaked and satisfies a single-crossing property for any two different numbers of potential players. However, total equilibrium spending is monotonically increasing in p and n. We also demonstrate that ex-post over-dissipation is a feature of the pure-strategy equilibrium in our model. It turns out that if the contest designer can strategically decide whether to reveal the actual number of participating players or not, then the actual number of participants is always revealed.

Competitive Behavior in Market Games: Evidence and Theory

We explore whether competitive outcomes arise in an experimental implementation of a market game, introduced by Shubik (1973) [21]. Market games obtain Pareto inferior (strict) Nash equilibria, in which some or possibly all markets are closed. We find that subjects do not coordinate on autarkic Nash equilibria, but favor more efficient Nash equilibria in which all markets are open. As the number of subjects participating in the market game increases, the Nash equilibrium they achieve approximates the associated competitive equilibrium of the underlying economy. Motivated by these findings, we provide a theoretical argument for why evolutionary forces can lead to competitive outcomes in market games.

Bertrand competition with intertemporal demand

In the text-book model of dynamic Bertrand competition, competing firms meet the same demand function every period. This is not a satisfactory model of the demand side if consumers can make intertemporal substitution between periods. Each period then leaves some residual demand to future periods, and consumers who observe price under-cutting may correctly anticipate an ensuing price war and therefore postpone their purchases. Accordingly, the interaction between the firms no longer constitutes a repeated game, and hence falls outside the domain of the usual Folk theorems. We analyze collusive pricing in such situations, and study cases when consumers have perfect and imperfect foresight and varying degrees of patience. It turns out that collusion against patient and forward-looking consumers is easier to sustain than collusion in the text-book model.

Lloyd Shapley and chess with imperfect information

Anyone who has ever studied game theory knows the name Lloyd Shapley. Just recall Matching, Deferred-Acceptance Algorithm, Core, Market Games, Stochastic Games, Shapley value, and Shapley vector.1 But Professor Shapley was also a great lover of chess with imperfect information. Upon our first encounter at Stony Brook in 1998, I was fortunate to investigate the chess problems he set before me. In this essay I analyze some of those problems, in commemoration of Lloyd Shapleys contributions to the study of chess and chess with imperfect information.

Coordination in a changing environment

In this paper we consider a model where boundedly rational agents choose both which coordination game to play and what action to take in that game, when their information and mobility is limited and change over time. We completely characterize both short-run and long-run outcomes. There are multiple types of short-run predictions in which agents may be at different locations, taking different actions. In the long-run, however, all agents are at the same location and take the same action in that game. The long-run prediction is unique and globally efficient most of the time.