3 citations · 3 across the 1 of their papers we have counts for
4 papers
Efficient Handling of SPARQL OPTIONAL for OBDA (Extended Version)
Guohui Xiao, Roman Kontchakov, Benjamin Cogrel +2
OPTIONAL is a key feature in SPARQL for dealing with missing information. While this operator is used extensively, it is also known for its complexity, which can make efficient eva…
Ontology-Mediated Queries: Combined Complexity and Succinctness of Rewritings via Circuit Complexity
Meghyn Bienvenu, Stanislav Kikot, Roman Kontchakov +2
We give solutions to two fundamental computational problems in ontology-based data access with the W3C standard ontology language OWL 2 QL: the succinctness problem for first-order…
Theoretically Optimal Datalog Rewritings for OWL 2 QL Ontology-Mediated Queries
Meghyn Bienvenu, Stanislav Kikot, Roman Kontchakov +2
We show that, for OWL 2 QL ontology-mediated queries with (i) ontologies of bounded depth and conjunctive queries of bounded treewidth, (ii) ontologies of bounded depth and bounded…
On the Decidability of Connectedness Constraints in 2D and 3D Euclidean Spaces
Roman Kontchakov, Yavor Nenov, Ian Pratt-Hartmann +1
We investigate (quantifier-free) spatial constraint languages with equality, contact and connectedness predicates as well as Boolean operations on regions, interpreted over low-dim…