Xcerpt is a Query and Transformation Language for XML and Semistructured data. Instead of the navigational approach of XPath-based languages like XSLT or XQuery, Xcerpt uses patterns for querying and is based on concepts of logic programming like unifica
A set of MediaWiki extensions and other tools developed for the Twelf wiki (http://twelf.plparty.org) that enable a wiki to naturally incorporate logic Twelf in a number of meaningful and useful ways.