Issue
EPL
Volume 81, Number 2, January 2008
Article Number 28005
Number of page(s) 6
Section Interdisciplinary Physics and Related Areas of Science and Technology
DOI http://dx.doi.org/10.1209/0295-5075/81/28005
Published online 10 December 2007
EPL, 81 (2008) 28005
DOI: 10.1209/0295-5075/81/28005

The entropy of randomized network ensembles

Ginestra Bianconi

The Abdus Salam International Center for Theoretical Physics - Strada Costiera 11, 34014 Trieste, Italy


received 3 September 2007; accepted in final form 19 November 2007; published January 2008
published online 10 December 2007

Abstract
Randomized network ensembles are the null models of real networks and are extensively used to compare a real system to a null hypothesis. In this paper we study network ensembles with the same degree distribution, the same degree correlations and the same community structure of any given real network. We characterize these randomized network ensembles by their entropy, i.e. the normalized logarithm of the total number of networks which are part of these ensembles. We estimate the entropy of randomized ensembles starting from a large set of real directed and undirected networks. We propose entropy as an indicator to assess the role of each structural feature in a given real network. We observe that the ensembles with fixed scale-free degree distribution have smaller entropy than the ensembles with homogeneous degree distribution indicating a higher level of order in scale-free networks.

PACS
89.75.-k - Complex systems.
89.75.Fb - Structure and organization in complex systems.
89.75.Hc - Networks and genealogical trees.

© EPLA 2008