42 search results - page 4 / 9 » Data Complexity of Query Answering in Expressive Description... |
DLOG
2011
12 years 11 months ago
2011
W3C currently extends the SPARQL query language with so-called entailment regimes, which define how queries are evaluated using logical entailment relations. We describe a sound a...
AAAI
2012
11 years 10 months ago
2012
We tackle the problem of defining a well-founded semantics (WFS) for Datalog rules with existentially quantified variables in their heads and negations in their bodies. In partic...
ICDT
2012
ACM
11 years 10 months ago
2012
ACM
Previous studies of incomplete XML documents have identified three main sources of incompleteness – in structural information, data values, and labeling – and addressed data ...
KR
2010
Springer
14 years 13 days ago
2010
Springer
Ontologies can be used to provide an enriched vocabulary for the formulation of queries over instance data. We identify query emptiness and predicate emptiness as two central reas...
PODS
1998
ACM
13 years 12 months ago
1998
ACM
We study the complexity of the problem of answering queries using materialized views. This problem has attracted a lot of attention recently because of its relevance in data integ...