62 search results - page 4 / 13 » Containment of Conjunctive Queries over Databases with Null ... |
PODS
2010
ACM
14 years 1 days ago
2010
ACM
For many problems arising in the setting of graph querying (such as finding semantic associations in RDF graphs, exact and approximate pattern matching, sequence alignment, etc.)...
PODS
2010
ACM
14 years 1 days ago
2010
ACM
We investigate a higher-order query language that embeds operators of the positive relational algebra within the simply-typed λ-calculus. Our language allows one to succinctly de...
VLDB
2007
ACM
14 years 7 months ago
2007
ACM
Views over probabilistic data contain correlations between tuples, and the current approach is to capture these correlations using explicit lineage. In this paper we propose an al...
GVD
2004
13 years 8 months ago
2004
Abstract. Checking the consistency of query conditions is an old problem, and there are already many proposed solutions. Since the problem is in general undecidable, there is not a...
ICDT
2001
ACM
13 years 11 months ago
2001
ACM
In information-integration systems, source relations often have limitations on access patterns to their data; i.e., when one must provide values for certain attributes of a relatio...