Symmetry in complex networks

We consider the size and structure of the automorphism groups of a variety of empirical 'real-world' networks and find chat, in contrast to classical random graph models, many real-world networks are richly symmetric. We Construct a practical network automorphism group decomposition, relate automorphism group structure to network topology and discuss generic forms of symmetry and their origin in real-world networks. We also comment on how symmetry can affect network redundancy and robustness. (C) 2008 Elsevier B.V. All rights reserved.