Random matching models with a continuum population are widely used in economics to study environments where agents interact in small coalitions. This paper provides foundations to such models. In particular, the paper establishes an existence result for random matchings that are universal in the...

Many economic models include random shocks imposed on a large number (continuum) of economic agents with individual risk. In this context, an exact law of large numbers and its converse is presented in Sun (2006) to characterize the cancelation of individual risk via aggregation. However, it is...

Purification results are important in game theory and statistical decision theory. The purpose of this paper is to prove a general purification theorem that generalizes many authors' results. The key idea of our proof is to make use of the exact law of large numbers. As an application, we show...

We study stable behavior when players are randomly matched to play a game, and before the game begins each player may observe how his partner behaved in a few interactions in the past. We present a novel modeling approach and we show that strict Nash equilibria are always stable in such...

Numerous economic models employ a continuum of negligible agents with a sequence of idiosyncratic shocks and random matchings. Several attempts have been made to build a rigorous mathematical justification for such models, but these attempts have left many questions unanswered. In this paper, we...

The paper studies an evolutionary model where players from a given population are randomly matched in pairs each period to play a co- ordination game. At each instant, a player can choose to adopt one of the two possible behavior rules, called the rational rule and the as- piring rule, and then...

Many economic models use a continuum of negligible agents to avoid considering one person's effect on aggregate characteristics of the economy. Along with a continuum of agents, these models often incorporate a sequence of independent shocks and random matchings. Despite frequent use of such...

The role of distinct currencies is studied using a random-matching model with randomized trades. The equilibrium concept is the pairwise core in meetings. We show that there exist equilibria in which home and foreign currency play distinct roles and in which the quantities of trade and output...