We propose that through the formalization of concepts related to trust, a more accurate model of trust can be implemented, This paper presents a new model of trust that is based on the formalization of reputation, A multidisciplinary approach is taken to understanding the nature of trust and its relation to reputation, Through this approach, a practical definition of reputation is adopted from sociological contexts and a model of reputation is designed and presented. Reputation is defined as role fulfillment. To formalize reputation, it is necessary to formalize the expectations placed upon an agent within a particular multi-agent system (MAS). In this case, the agents are part of an information-sharing society. Five roles are defined along with the ways in which these roles are objectively fulfilled, Through the measurement of role fulfillment, a vector representing reputation can be developed, This vector embodies the magnitude of the reputation and describes the patterns of behavior associated with the direction of the vector. Experiments are conducted to verify the sensibility of the proposed models for role fulfillment and overall reputation. The simulation results show that the roles, defined for building reputation in an information-sharing MAS environment, react to different agent and user actions in a manner consistent with the formal definitions.
