Reasoning about XML Constraints based on XML-to-relational mappings

Matthias Niewerth

We introduce a simple framework for the specification of constraints for XML documents and study the implication problem for some instantiations of the framework. The specification of a constraint in this framework consists of (1) a mapping that extracts a relation from every XML document and (2) a relational constraint on the resulting relation. The mappings can be arbitrary but the intension is that they only refer to the structure of the XML document (but can yield both document nodes and data values). The relational constraints can be of any kind. As a typical example, we study the implication problem for XML constraints that are specified by tree pattern queries and functional dependencies.