Norm Emergence: Overcoming Hub Effects in Scale Free Networks

Mahmoud, S., Griffths, N., Keppens, J. and Luck, M.

Proceedings of the 14th International Workshop on Coordination, Organisations, Institutions and Norms. 136-150.

June 2012

Abstract

As has been stated elsewhere, norms are a valuable means of establishing coherent cooperative behaviour in decentralised systems in which there is no central authority. Axelrod’s seminal model of norm establishment in populations of self-interested individuals provides some insight into the mechanisms needed to support this through the use of metanorms, but considers only limited scenarios and domains. While further developments of Axelrod’s model have addressed some of the limitations, in particular in considering its application to different topological structures, this too has been limited in not offering an effective means of bringing about norm compliance in scale-free networks, due to the problematic effects of hubs. This paper offers a solution, first by adjusting the model to more appropriately reflect the characteristics of the problem, and sec- ond by offering a new dynamic policy adaptation approach to learning the right behaviour. Experimental results demonstrate that this dynamic policy adaptation overcomes the difficulties posed by asymmetric distribution of links in scale-free networks, leading to an absence of norm violation, and instead norm emergence.

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