376 search results - page 21 / 76 » Semantics and Evaluation of Top-k Queries in Probabilistic D... |
CORR
2007
Springer
13 years 7 months ago
2007
Springer
We address the problem of answering Web ontology queries efficiently. An ontology is formalized as a Deductive Ontology Base (DOB), a deductive database that comprises the ontology...
EDBT
2006
ACM
14 years 8 months ago
2006
ACM
In this paper we present a novel approach for estimating the selectivity of XML twig queries. Such a technique is useful for approximate query answering as well as for determining...
PODS
2009
ACM
14 years 8 months ago
2009
ACM
We consider the problem of deciding query equivalence for a conjunctive language in which queries output complex objects composed from a mixture of nested, unordered collection ty...
ICDT
2007
ACM
14 years 2 months ago
2007
ACM
Abstract. We study containment of conjunctive queries that are evaluated over databases that may contain tuples with null values. We assume the semantics of SQL for single block qu...
PODS
2006
ACM
14 years 8 months ago
2006
ACM
Query containment is a fundamental algorithmic problem in database query processing and optimization. Under set semantics, the query-containment problem for conjunctive queries ha...