In this paper we present the theoretical and methodological foundations for the development of a multi-agentN owadays, one of the main challenges faced by information systems at libraries or on the Web is to efficiently manage the large number of documents they hold. Information systems make it easier to give users access to relevant resources that satisfy their information needs, but a problem emerges when the user has a high degree of specialization and requires very specific resources, as in the case of researchers.1 In "traditional" physical libraries, several procedures have been proposed to try to mitigate this issue, including the selective dissemination of information (SDI) service model that make it possible to offer users potentially interesting documents by accessing users' personal profiles kept by the library.Nevertheless, the progressive incorporation of new information and communication technologies (ICTs) to information services, the widespread use of the Internet, and the diversification of resources that can be accessed through the Web has led libraries through a process of reinvention and transformation to become "digital" libraries.2 This reengineering process requires a deep revision of work techniques and methods so librarians can adapt to the new work environment and improve the services provided.In this paper we present a recommendation and SDI model, implemented as a service of a specialized digital library (in this case, specialized in library and information science), that can increase the accuracy of accessing information and the satisfaction of users' information needs on the Web. This model is built on a multi-agent framework, similar to the one proposed by Herrera-Viedma, Peis, and Morales-del-Castillo, 3 that applies Semantic Web technologies within the specific domain of specialized digital libraries in order to achieve more efficient information management (by semantically enriching different elements of the system) and improved agent-agent and user-agent communication processes. Furthermore, the model uses fuzzy linguistic modelling techniques to facilitate the user-system interaction and to allow a higher grade of automation in certain procedures. To increase improved automation, some natural language processing (NLP) techniques are used to create a system thesaurus and other auxiliary tools for the definition of formal representations of information resources.In the next section, "Instrumental basis," we briefly analyze SDI services and several techniques involved in the Semantic Web project, and we describe the preliminary methodological and instrumental bases that we used for developing the model, such as fuzzy linguistic modelling techniques and tools for NLP. In "Semantic SDI service model for digital libraries," the bulk of this work, the application model that we propose is presented. Finally, to sum up, some conclusive data are highlighted.n Instrumental basis
Filtering techniques for SDI servicesFiltering and recommendation services are based on the application of dif...