Many conditions have been introduced to weaken the continuity re-quirements for equilibrium existence in games. We introduce a new con-dition, called regularity, that is simple and easy to verify. It is implied both by Reny's better-reply security and Simon and Zame's endogenous sharing rule...

We seek an evolutionary explanation for why in some situations humans maintain either optimistic or pessimistic attitudes towards uncertainty and are ignorant to relevant aspects of their environment. Players in strategic games face Knightian uncertainty about opponents' actions and maximize...

It is well known that the rock-paper-scissors game has no pure saddle point. We show that this holds more generally: A symmetric two-player zero-sum game has a pure saddle point if and only if it is not a generalized rock-paper-scissors game. Moreover, we show that every finite symmetric...

Schelling (1969, 1971a,b, 1978) considered a simple proximity model of segregation where individual agents only care about the types of people living in their own local geographical neighborhood, the spatial structure being represented by one- or two-dimensional lattices. In this paper, we argue...

We present a non-technical account of ambiguity in strategic games and show how it may be applied to economics and social sciences. Optimistic and pessimistic responses to ambiguity are formally modelled. We show that pessimism has the effect of increasing (decreasing) equilibrium prices under...

We analyse the all-pay auction with incomplete information and variance-averse bidders. We characterise the symmetric equilibrium for general distributions of valuations and any number of bidders. Variance aversion is a sufficient assumption to predict that high-valuation bidders increase their...

We consider a two group contest over a group specific public good comparing two situations: (i) when all players act independently; and (ii) when the players of each group cooperate. This comparison leads us to the conclusion that it is possible for one group to contribute more (and have a...

In models of non-deterministic contest, players exert irreversible effort in order to increase their probability of winning a prize. The most prominent functional form of the win probability in the literature is the so-called logit" contest success function. We provide a simple micro-foundation...

Regret minimizing strategies for repeated games have been receiving increasing attention in the literature. These are simple adaptive behavior rules that exhibit nice convergence properties. If all players follow regret minimizing strategies, their average joint play converges to the set of...