XPath-logic and XPathLog: A logic-programming style XML data manipulation language

We define XPathLog as a Datalog-style extension of XPath. XPathLog provides a clear, declarative language for querying and manipulating XML whose perspectives arc especially in XML data integration. In Our characterization, the formal semantics is defined wrt. an edge-labeled graph-based model, which covers the XML data model. We give a complete, logic-based characterization of XML data and the main language concept Cor XML, XPath. XPath-Logic extends the XPath language with variable bindings and embeds it into first-order logic. XPathLog is then the Horn fragment of XPath-Logic, providing a Datalog-style, rule-based language for querying and manipulating X M L data. The model-theoretic semantics of XPath-Logic serves as the base of XPathLog as a logic-programming language, whereas also an equivalent answer-set semantics for evaluating XPathLog queries is given. In contrast to other approaches, the XPath syntax and semantics is also used for a declarative specification how the database Should be updated : when used in rule heads, XPath filters are interpreted as specifications of elements and properties Which Should he added to the database.