Integrating Trust Measures in Multiagent Systems Domenico Rosaci, ∗ Giuseppe M.L. Sarn ´ e, † Salvatore Garruzzo ‡ DIMET, Universit` a Mediterranea di Reggio Calabria, Via Graziella, Localit ` a Feo di Vito, 89122 Reggio Calabria, Italy Several models have been proposed in the past for representing both reliability and reputation. However, we remark that a crucial point in the practical use of these two measures is represented by the possibility of suitably combining them to support the agent’s decision. In the past, we proposed a reliability–reputation model, called RRAF, that allows the user to choose how much importance to give to the reliability with respect to the reputation. However, RRAF shows some limitations, namely: (i) The weight to assign to the reliability versus reputation is arbitrarily set by the user, without considering the system evolution; (ii) the trust measure that an agent a perceives about an agent b is completely independent of the trust measure perceived by each other agent c, while in the reality the trust measures are mutually dependent. In this paper, we propose an extension of RRAF, aiming at facing the limitations above. In particular, we introduce a new trust reputation model, called TRR, that considers, from a mathematical viewpoint, the interdependence among all the trust measures computed in the systems. Moreover, this model dynamically computes a parameter measuring the importance of the reliability with respect to the reputation. Some experiments performed on the well-known ART(Agent Reputation and Trust) platform show the significant advantages in terms of effectiveness introduced by TRR with respect to RRAF. C  2011 Wiley Periodicals, Inc. 1. INTRODUCTION Over the last recent years, the introduction of trust-based approaches in multiagent systems (MAS) has been recognized as a promising solution to improve the effectiveness of these systems. 1–3 It is a matter of fact that nowadays MASs are more and more exploited in several application domains to provide e-services, such as e-Commerce, e-Learning, and so on. In such a context, software agents are distributed in large-scale networks and interact to share resources with each other. Trust is essential in such settings to make social interactions much fruitful as ∗ Author to whom all correspondence should be addressed: e-mail: domenico.rosaci@ unirc.it. † e-mail: sarne@unirc.it. ‡ e-mail: salvatore.garruzzo.@unirc.it. INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, VOL. 27, 1–15 (2012) C  2011 Wiley Periodicals, Inc. View this article online at wileyonlinelibrary.com. • DOI 10.1002/int.20513