This position paper describes planned research on the retrieval component of the Profile Information Filtering Project of the University of Nijmegen. The Profile project is a joint research project of researchers from four related areas, including computing and cognitive sciences. The overall organizational structure of the Profile project is outlined to illustrate the place of the retrieval component within the Profile project. This component is called the Retrieval Engine and is to be implemented as a multi-agent system, consisting of several types of proactive agents. A synthesis between Information Retrieval and Information Filtering has to be found, coping with problems stemming from the combination of both fields. A way has to be found in which those aspects can be integrated in multi-agent technology. In stead of keywords, noun phrases will be used as building blocks for the query and characterization languages. The matching techniqueswill thus have to support those languages. Based on thematching process, an explanation of why a document is considered relevant can be given. This requires the matching functions to include a symbolic part.