A@lying Bayesian Networks to In#ormation Retrieval

nformation retzieval (IR) is the identification of docu- ments or other units of information in a collection that are relevant to a particular information need. An infor- mation need is a set of questions to which someone would like to find an answer. Here are some examples of IR tasks: finding articles in the New York Times that discuss the Iran-Contra affair, searching the recent post- ings in a Usenet newsgroup for references to a particular model of personal computer; finding the entries refer- ring to butterflies in an online CDROM encyclopedia.

The use of IR systems is increasing with the growing popularity of electronic media as a way to publish and exchange information. There are online electronic dic- tionaries, encyclopedias, recipe files, and newspapers, provided on personal computer CDROMs, through commercial dial-up online services, or over the Internet using WAIS and Gopher. Because of the large size of modern document collections, providing tools to assist users in retrieving information of interest is of growing importance.

All IR systems draw conclusions about the content of a document by examining some representation of that