A risky skill game is a game in which skill plays an important role but outcomes are also strongly influenced by random factors. Examples are poker or blackjack but also many economic activities like trading on financial markets. In an online experiment we let subjects choose how often they want...

The Savage and the Anscombe-Aumann frameworks are the two most popular approaches used when modeling ambiguity. The former is more flexible, but the latter is often preferred for its simplicity. We conduct an experiment where subjects place bets on the joint outcome of an ambiguous urn and a...

We characterize the class of symmetric two-player games in which tit-for-tat cannot be beaten even by very sophisticated opponents in a repeated game. It turns out to be the class of exact potential games. More generally, there is a class of simple imitation rules that includes tit-for-tat but...