SIR: a Model of Social Reputation

In a Virtual Society (VS) context, possibly federated and mutually distrustful entities (i.e., individuals and resources) interact with each other, providing and consuming services, in order to achieve their own goals. Within this context, reputation management has been identified as a possible mean to enable entities to decide whether and at which conditions to engage interactions with other entities; moreover, reputation management can provide any entity within a group with an expectation about the result of a possible interaction with any other. In this document we present SIR, the novel reputation model that has been designed getting inspiration by how reputation forms and propagates in the human society; the novelty of SIR is that its flexibility enables a reputation system to be set up in any possible virtual society scenario and its robustness enables entities to ignore byzantine informations that are injected within the reputation system. Moreover, we present TAw, an implementation of the SIR reputation model that enables trust awareness to be implemented over any existing naming service; thus, TAw provides entities in distributed settings to manage the interactions with each other in a trust-aware manner. We discuss simulation results that show the benefits that can be achieved by the application of the SIR reputation model within a naming service. These experimental results also show that the SIR reputation model enables the implementation of adaptive, robust, and scalable reputation management systems. 2. This work has been partially supported by the European FP5 RTD project TAPAS (IST-2001-34069) and by the base project “WebMiNDS” under the FIRB program of the Italian Ministry of Education, University and Research. 3. Dept. of Computer Science, University of Bologna, 7, Mura Anteo Zamboni, 40127 Bologna, ITALY, e-mail: [email protected], homepage: http://www.cs.unibo.it/ ̃mezzettn