The norm game - how a norm fails
  We discuss the simulations of the norm game between players at nodes of a directed random network. The final boldness of the players can vary with the initial one as the $\Theta$ function. One of the conditions of this behaviour is that the player who does not punish automatically becomes a defector. The threshold value of the initial boldness can be interpreted as a norm strength. It increases with the punishment and decreases with its cost. Surprisingly, it also decreases with the number of potential punishers. The numerical results are discussed in the context of the statistical data on crimes in Northern Ireland and New Zealand, on divorces in USA, and on the alcohol consumption in Poland. 
Krzysztof Kulakowski and Antoni Dydejczyk