More than 50 years ago, at a time when modern computers didn't exist yet, Vannevar Bush wrote about a multimedia digital library containing human collective knowledge and filled with "trails" linking materials of the same topic. At the end of World War II, Vannevar urged scientists to build such a knowledge store and make it useful, continuously extendable and more importantly, accessible for consultation. Today, the closest to the materialization of Vannevar's dream is the World-Wide Web hypertext and multimedia document collection. However, the ease of use and accessibility of the knowledge described by Vannevar is yet to be realized. Since the 60s, extensive research has been accomplished in the information retrieval field, and free-text search was finally adopted by many text repository systems in the late 80s. The advent of the World-Wide Web in the 90s helped text search become routine as millions of users use search engines daily to pinpoint resources on the Internet. However, r...

We present a method for retrieving concepts from web search queries and from candidate documents on the web, to help determine which of these documents are semantically (rather than simply key-word wise) related to the query. Our method combines hypothetical reasoning, which we use both for natural language analysis and for concept extraction, and domain-oriented taxonomies of concepts to guide the system's reasoning. 1 Introduction Realistic natural language analysis, whether for web or traditional applications, cannot make abstraction of semantics and pragmatics, any more than programming languages can fully make abstraction of their run-time environments. Computer-based discourse understanding (as its human counterpart) is basically a form of model-building. It involves constant constraint-solving to keep, at a given time, only a manageable subset of (intended) models. The task is harder, but similar to that of compilers for programming languages. The experience of being drowned wi...