Abstract: A method and apparatus are provided for generating and updating a concept dictionary 140 in respect of an information system 125 and for using that concept dictionary to assist in selecting queries and query terms for use in interrogating that information system 125. A lexical reference source 115 is first used to generate queries semantically related to a query 110 entered by a user, and the answers returned for each query are analysed using a fuzzy processing technique (135) to determine semantic relationships between the queries. The queries and the determined relationships are recorded in a concept dictionary 140 for subsequent use.