61 citations · 129 across the 10 of their papers we have counts for
9 papers · 1 filter
First-Order Rewritability of Frontier-Guarded Ontology-Mediated Queries
Pablo Barcelo, Gerald Berger, Carsten Lutz +1
We focus on ontology-mediated queries (OMQs) based on (frontier-)guarded existential rules and (unions of) conjunctive queries, and we investigate the problem of FO-rewritability,…
When is Ontology-Mediated Querying Efficient?
Pablo Barcelo, Cristina Feier, Carsten Lutz +1
In ontology-mediated querying, description logic (DL) ontologies are used to enrich incomplete data with domain knowledge which results in more complete answers to queries. However…
The Limits of Efficiency for Open- and Closed-World Query Evaluation Under Guarded TGDs
Pablo Barcelo, Victor Dalmau, Cristina Feier +2
Ontology-mediated querying and querying in the presence of constraints are two key database problems where tuple-generating dependencies (TGDs) play a central role. In ontology-med…
On the Expressiveness of LARA: A Unified Language for Linear and Relational Algebra
Pablo Barceló, Nelson Higuera, Jorge Pérez +1
We study the expressive power of the LARA language -- a recently proposed unified model for expressing relational and linear algebra operations -- both in terms of traditional data…
A More General Theory of Static Approximations for Conjunctive Queries
Pablo Barceló, Miguel Romero, Thomas Zeume
Conjunctive query (CQ) evaluation is NP-complete, but becomes tractable for fragments of bounded hypertreewidth. Approximating a hard CQ by a query from such a fragment can thus al…
Boundedness of Conjunctive Regular Path Queries
Pablo Barceló, Diego Figueira, Miguel Romero
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 t…