Token-templates and logic programs for intelligent web search

We present a general framework for the information extraction from web page s based on a special wrapper language, called token-templates. By using tok en-templates in conjunction with logic programs we are able to reason about web page contents, search and collect facts and derive new facts from vari ous web pages. We give a formal definition for the semantics of logic progr ams extended by token-templates and define a general answer-complete calcul us for these extended programs. These methods and techniques are used to bu ild intelligent mediators and web information systems.