Similarity-based queries for information retrieval

This paper presents a formal framework for queries based on similarity in fuzzy information retrieval systems. It is well known that a mechanism for improving the retrieval recall is the use of broader terms or specific terms to the terms that appears in the original query. The devices of expansion of queries use fuzzy thesauri and the notion of hierarchies. The formal framework presents three components: T, the set of all the terms in the system, Gamma, the set of transformation rules applied on T, L, the flexible query language. This framework is based on the fuzzy set theory.