US Patent 7877400 Optimizations of XPaths

Methods and apparatus, including computer program products, for searching for one or more logical elements in a hierarchical tree structure of an extended markup language document conforming to a schema used for XML. The method includes the steps of (1) providing a representation of an extended markup language document instance containing two or more logical elements, one being a parent node and one a child node in a hierarchical tree structure describing the representation; (2) receiving a query for logical elements satisfying an XPath expression; and (3) searching in the hierarchical tree structure only nodes that potentially have child nodes satisfying the XPath expression.