A Study of a Positive Fragment of Path Queries: Expressiveness, Normal Form and Minimization Universiteit Hasselt Universiteit Antwerpen
We study the expressiveness of a positive fragment of path queries, denoted Path(+), on documents that can be represented as node-labeled trees. The expressiveness of Path(+) is studied from two angles. First, we establish that Path(+) is equivalent in expressive power to two particular subfragments, as well as to the class of tree queries, a subclass of the first-order conjunctive queries defined over the label, parent-child and child-parent ...