This discussion paper resulted in a publication in the <I>International Game Theory Review</I> (2007). Vol. 9(4), pp. 599-635.<P> It is widely recognized that the shape of networks influences both individual and aggregate behavior. This raises the question which types of networks are likely to arise. Our...</p></i>

It is widely recognized that the shape of networks influences both individual and aggregate behavior. This raises the question which types of networks are likely to arise. Our paper fits into the literature that addresses this question. The paper continues on the work of Galeotti, Goyal and...

This discussion paper resulted in a publication in the <I>Journal of Economic Behavior & Organization</I> (2008), volume 66, pages 243-250.<P> We study fairness and reciprocity in a Hawk-Dove game. This alllows us to testvarious models in one framework. We observe a large extent of selfish and...</p></i>

The effects of stake size on cooperation and punishment are investigated using a public goods experiment. We find that an increase in stake size does neither significantly affect cooperation nor, interestingly, the level of punishment.

Explaining the evolution and maintenance of cooperation among unrelated individuals is one of the fundamental problems in biology and the social sciences. Recent experimental evidence suggests that altruistic punishment is an important mechanism to maintain cooperation among humans. In this...