Analysis of a robust reputation system for self‐organised networks

Self‐organised networks require some mechanism to ensure cooperation and fairness. A promising approach is the use of decentralised reputation systems. However, their vulnerability to liars has not yet been analysed in detail. In this paper, we provide a first step to the robustness analysis of a reputation system based on a deviation test. Users accept second‐hand information only if this does not differ too much from their reputation values. We simplify the original system in order to obtain a one‐dimensional formulation and show that it exhibits a phase transition. In the subcritical regime, the reputation system is robust. In the supercritical regime, lying has an impact. We obtain the critical values via a mean‐field approach and verify the results by explicit computation. Thus, we provide conditions for the deviation test to make the reputation system robust as well as quantitative results on what goes wrong in the supercritical regime. Copyright © 2005 AEIT.