Definability for Downward and Vertical XPath on Data Trees
نویسندگان
چکیده
We study the expressive power of the downward and vertical fragments of XPath equipped with (in)equality tests over data trees. We give necessary and sufficient conditions for a class of pointed data trees to be definable by a set of formulas or by a single formula of each of the studied logics. To do so, we introduce a notion of saturation, and show that over saturated data trees bisimulation coincides with logical equivalence.
منابع مشابه
Saturation, Definability, and Separation for XPath on Data Trees
We study the expressive power of some fragments of XPath equipped with (in)equality tests over data trees. Our main results are the definability theorems, which give necessary and sufficient conditions under which a class of data trees can be defined by a node expression or set of node expressions, and our separation theorems, which give sufficient conditions under which two disjoint classes of...
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