Satisfiability of Downward XPath with Data Equality Tests

Diego Figueira (1)

1 LSV - Laboratoire Spécification et Vérification [Cachan]

In this work we investigate the satisfiability problem for the logic XPath(↓*, ↓, =), that includes all downward axes as well as equality and inequality tests. We address this problem in the absence of DTDs and the sibling axis. We prove that this fragment is decidable, and we nail down its complexity, showing the problem to be ExpTime-complete. The result also holds when path expressions allow closure under the Kleene star operator. To obtain these results, we introduce a new automaton model over data trees that captures XPath(↓*, ↓, =) and has an ExpTime emptiness problem. Furthermore, we give the exact complexity of several downward-looking fragments.

Mots clés: XML; XPath; unranked unordered tree; data- tree; infinite alphabet; data values

Domaines: Base de données [cs.DB]; Théorie et langage formel [cs.FL]; Mathématique discrète [cs.DM]; Logique en informatique [cs.LO]

Diego Figueira. Satisfiability of Downward XPath with Data Equality Tests. Symposium on Principles of Database Systems (PODS), Jun 2009, Providence (RI), United States. ⟨hal-02382925⟩