Creating and Using Reputation-based Agreements in Organisational Environments ⋆ Roberto Centeno 1 , Ram´on Hermoso 1 , and Viviane Torres da Silva 2 {roberto.centeno, ramon.hermoso}@urjc.es, viviane.silva@ic.uff.br 1 Centre for Intelligent Information Technologies (CETINIA) University Rey Juan Carlos Madrid (URJC) - Spain 2 Universidade Federal Fluminense (UFF) - Brazil Abstract. Reputation mechanisms have been developed during last few years as valid methods to allow agents to better select partners in or- ganisational environments. In most of works presented in the literature, reputation is summarised as a value, typically a number, that represents an opinion sent by an agent to another about a certain third party. In this work, we put forward a novel concept of reputation-based agreement in order to support the reputation definition, as well as, some desirable properties about it. We define a reputation service that collects opinions from agents, so creating agreements over situations. This service will also be in charge of presenting the information by using different informative mechanisms. Finally, a case study is presented in order to exemplify our work. 1 Introduction Reputation mechanisms have been proved to be successful methods to build multi-agent systems where agents’ decision-making processes to select partners are crucial for the system functioning [4][5][8]. In models such as in [5][8] the authors focus on let the agent the duty of requesting opinions, aggregating replies and inferring conclusions from the gathered information. In this work we do not intend to leave those duties apart, but complementary endow organisations with a reputation service that may help agents to make decisions when they do not have enough relevant stored information. In this paper we introduce the concept of reputation-based agreement as the cornerstone of the reputation service in an organisational multi-agent system. An agreement is usually defined as a meeting of minds between two or more parties, about their relative duties and rights regarding current or future performance. Around this concept new paradigms have been emerged [1] oriented to increase the reliability and performance of agents in organisations by introducing in such ⋆ The primary author of the paper is a student. The present work has been partially funded by the Spanish Ministry of Education and Science under project TIN2006- 14630-C03-02 (FPI grants program) and by the Spanish project “Agreement Tech- nologies” (CONSOLIDER CSD2007-0022, INGENIO 2010)