Networks are one of the essential building blocks of society. Not only do firms cooperate in R&D networks, but firms themselves may be seen as networks of information-exchanging workers. Social movements increasingly make use of networks to exchange information, just as on the negative side...

This paper presents a game-theoretic rationale for the beneficial effect of a common enemy on cooperation. In a defence game against a common natural threat, the value of the public good of defence is equal to the sum of the players' defensive efforts. The game therefore takes the form of a...

"The enemy of my enemy is my friend." This common adage, which seems to be adhered to in social interactions (e.g. high school cliques or work relationships) as well as in political alliances within countries and between countries, describes the ability of groups or people to work together when...