Boundedness of Conjunctive Regular Path Queries - Archive ouverte HAL Access content directly
Conference Papers Year : 2019

Boundedness of Conjunctive Regular Path Queries


We study the boundedness problem for unions of conjunctive regular path queries with inverses (UC2RPQs). This is the problem of, given a UC2RPQ, checking whether it is equivalent to a union of conjunctive queries (UCQ). We show the problem to be ExpSpace-complete, thus coinciding with the complexity of containment for UC2RPQs. As a corollary, when a UC2RPQ is bounded, it is equivalent to a UCQ of at most triple-exponential size, and in fact we show that this bound is optimal. We also study better behaved classes of UC2RPQs, namely acyclic UC2RPQs of bounded thickness, and strongly connected UCRPQs, whose boundedness problem are, respectively, PSpace-complete and Pi^p_2-complete. Most upper bounds exploit results on limitedness for distance automata, in particular extending the model with alternation and two-wayness, which may be of independent interest.
Fichier principal
Vignette du fichier
main-hal.pdf (1.12 Mo) Télécharger le fichier
Origin : Files produced by the author(s)

Dates and versions

hal-02056388 , version 1 (04-03-2019)
hal-02056388 , version 2 (25-04-2019)



Pablo Barceló, Diego Figueira, Miguel Romero. Boundedness of Conjunctive Regular Path Queries. International Colloquium on Automata, Languages, and Programming (ICALP), Jul 2019, Patras, Greece. ⟨10.4230/LIPIcs.ICALP.2019.104⟩. ⟨hal-02056388v2⟩


225 View
133 Download



Gmail Facebook X LinkedIn More