There is a growing number of search engines that help users locate Web pages of potential interest. Most of these accept queries in natural language, perform fuzzy matching, and display records in ranked order of probable relevance. Some search engines perform query expansion to identify additional terms that are related to the user's query words, as well as query refinement to identify additional Web pages that are similar to those marked relevant by the user. Most do not accept natural language queries, requiring users to formulate queries in Boolean expressions. Records retrieved are not ranked, and no assistance with query expansion and query refinement is provided.
Current Web interfaces to OPACs are little better than traditional OPACs transplanted on the Web.
For an increasing number of people, Web search engines will be the type of information retrieval system they are most familiar with. E-Referencer is being developed as an answer to this question. It transforms a Boolean OPAC into a retrieval system with many of the search capabilities of Web search engines. E-Referencer encapsulates some of the knowledge and searching expertise of experienced librarians. It processes the user's natural language query, maps the query words to Library of Congress subject headings, selects a suitable search strategy and formulates an appropriate search statement to send to the library system.