Introduction With the number of World Wide Web sites growing every day, the problem is not just to find information, but to locate the right piece of information. Current solutions for structuring information, subject hierarchies and general search engines have both advantages and drawbacks.
Subject hierarchies are precise enough due to manual classification.
However, the number of results provided in response to an average query is usually low due to the small amount of documents indexed. General World Wide Web search engines, indexing most of the Web, return a long list of documents, but often to the detriment of precision. The search result is then barely usable because of the large number of answers from different domains and topics. Only complex queries may, in a given situation, produce a limited number of potentially relevant documents. To make searches more efficient and useful to ordinary users, we need intelligent and specialised search engines on the Net.