Containment of UC2RPQ: the hard and easy cases

Diego Figueira (1, 2)

1 LaBRI - Laboratoire Bordelais de Recherche en Informatique
2 CNRS - Centre National de la Recherche Scientifique

We study the containment problem for UC2RPQ, that is, two-way Regular Path Queries, closed under conjunction, projection and union. We show a dichotomy property between PSpace-c and ExpSpace-c in terms of the shape of queries, based on a property on its underlying graph. We show that for any class C of graphs, the containment problem for queries whose underlying graph is in C is in PSpace if and only if C has bounded bridgewidth. Bridgewidth is a graph measure we introduce, defined as the maximum size of a minimal edge separator of a graph.

Mots clés: Regular Path Queries (RPQ); 2RPQ; C2RPQ; UC2RPQ; graph databases; containment; inclusion; equivalence; dichotomy; graph measure; bridge-width (bridgewidth); minimal edge separator; minimal cut-set; max-cut; tree-width (treewidth)

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

Diego Figueira. Containment of UC2RPQ: the hard and easy cases. 2019. ⟨hal-02291888v1⟩