5 citations · 9 across the 12 of their papers we have counts for
8 papers · 1 filter
sheval: An RDF data shapes evaluation tool and test-suite for recursive shapes
Shqiponja Ahmetaj, Iovka Boneva, Jan Hidders +8
Two different languages have been developed to validate RDF data based on the concept of a shape: ShEx and SHACL. In each language it is possible to define a shape that refers to i…
Rewriting Ontology-Mediated Property Graph Queries into GQL
Bianca Löhnert, Nikolaus Augsten, Cem Okulmus +1
Ontology-based data access is intended for graph data, but practical support remains limited to SQL-like languages lacking the navigational and path-matching features fundamental t…
Common Foundations for SHACL, ShEx, and PG-Schema
S. Ahmetaj, I. Boneva, J. Hidders +11
Graphs have emerged as an important foundation for a variety of applications, including capturing and reasoning over factual knowledge, semantic data integration, social networks,…
Selective Use of Yannakakis' Algorithm to Improve Query Performance: Machine Learning to the Rescue
Daniela Böhm, Georg Gottlob, Matthias Lanzinger +4
Query optimization has played a central role in database research for decades. However, more often than not, the proposed optimization techniques lead to a performance improvement…
Soft and Constrained Hypertree Width
Matthias Lanzinger, Cem Okulmus, Reinhard Pichler +2
Hypertree decompositions provide a way to evaluate Conjunctive Queries (CQs) in polynomial time, where the exponent of this polynomial is determined by the width of the decompositi…
Towards Practicable Algorithms for Rewriting Graph Queries beyond DL-Lite
Bianca Löhnert, Nikolaus Augsten, Cem Okulmus +1
Despite the many advantages that ontology-based data access (OBDA) has brought to a range of application domains, state-of-the-art OBDA systems still do not support popular graph d…
Expressive Power and Complexity Results for SIGNAL, an Industry-scale Process Query Language
Timotheus Kampik, Cem Okulmus
With the increased adoption of process mining, there is also a need for practical solutions that work at industry scales. In this context, process querying methods (PQMs) have emer…
Structure-Guided Query Evaluation: Towards Bridging the Gap from Theory to Practice
Georg Gottlob, Matthias Lanzinger, Davide Mario Longo +3
Join queries involving many relations pose a severe challenge to today's query optimisation techniques. To some extent, this is due to the fact that these techniques do not pay suf…