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 based on a property on the underlying graph of queries. 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 to this end, defined as the maximum size of a minimal edge separator of a graph.
@InProceedings{figueira:LIPIcs.ICDT.2020.9, author = {Figueira, Diego}, title = {{Containment of UC2RPQ: The Hard and Easy Cases}}, booktitle = {23rd International Conference on Database Theory (ICDT 2020)}, pages = {9:1--9:18}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-139-9}, ISSN = {1868-8969}, year = {2020}, volume = {155}, editor = {Lutz, Carsten and Jung, Jean Christoph}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2020.9}, URN = {urn:nbn:de:0030-drops-119330}, doi = {10.4230/LIPIcs.ICDT.2020.9}, annote = {Keywords: Regular Path Queries (RPQ), 2RPQ, CRPQ, C2RPQ, UC2RPQ, graph databases, containment, inclusion, equivalence, dichotomy, graph measure, bridge-width (bridgewidth), minimal edge separator, minimal cut-set, max-cut, tree-width (treewidth)} }
Feedback for Dagstuhl Publishing