Fuzzy information retrieval systems: A historical perspective

The application of fuzzy set theory to information retrieval has been applied, specifically to Boolean models. This includes fuzzy indexing procedures defined to represent the varying significance of terms in synthesizing the documents' contents, the definition of query languages to allow the expression of soft selection conditions, and associative retrieval mechanisms to model fuzzy pseudo-thesauri, fuzzy ontologies, and fuzzy categorizations of documents.