We propose in project FERMI to develop a Retrieval Model for a new generation of IR systems handling every kind of data in any medium in an integrated manner through interaction with a user. The research will be conducted within a framework based on formal logics with associated theories of uncertainty. Retrieval will be viewed as a form of informative reasoning based on a notion of entailment subject to a measure of uncertainty, thus capturing quantitatively the probability of relevance of a stored object. The results of our research using suitable multimedia data will be tested within an experimental setting. The tests will use prototype implementations of algorithms whose computational complexity will have been investigated. An experimental design appropriate for large scale testing will be specified so that our results will be reported with statistical validity.