Abstract: An information retrieval system including a plurality of indices representative of information stored in the information retrieval system and a dynamic lexicon is disclosed. The system includes memory having a database stored therein, the database being logically divided to include the plurality of indices, an information database having information objects stored therein and a dynamic lexicon which includes a plurality of data items and groups of data items that appear in the information database. A predetermined time variable represents the last time the plurality of indices were reindexed. After changes are made to the lexicon, a time stamp is attached to each one of the plurality of changes to the lexicon to indicate when the change was made to the lexicon. At some specified time interval later, the reindexing process is invoked.

Abstract: A method and apparatus that translates a natural language query into a Boolean expression to be used to search a database. The Boolean expression is displayed on a screen so that the user can alter the Boolean expression using a mouse or similar input device and re-execute the search. The manipulations performed by the user include moving terms of the query, changing the order in which query terms are evaluated, adding terms, deleting terms, and selecting alternate versions of terms.