14.2 Defining Terms in a Thesaurus

You can create synonyms, related terms, and hierarchical relationships with a thesaurus.

This section contains the following topics.

• Defining Synonyms

• Defining Hierarchical Relations

14.2.1 Defining Synonyms

If you have a thesaurus of computer science terms, then you might define a synonym for the term XML as extensible markup language. This synonym enables queries on either of these terms to return the same documents.

XML

SYN Extensible Markup Language

You can use the SYN operator to expand XML into its synonyms:

'SYN(XML)'

is expanded to:

'XML, Extensible Markup Language'

14.2.2 Defining Hierarchical Relations

If your document set consists of news articles, you can use a thesaurus to define a hierarchy of geographical terms. Consider the following that describes a geographical hierarchy for the state of California:

California
   NT Northern California
       NT San Francisco
       NT San Jose
   NT Central Valley
       NT Fresno
   NT Southern California
       NT Los Angeles

You can use the NT operator to expand a query on California:

'NT(California)'

is expanded to:

'California, Northern California, San Francisco, San Jose, Central Valley,
  Fresno, Southern California, Los Angeles'

The resulting hitlist shows all documents related to the state of California regions and cities.