121 search results - page 6 / 25 » On Containment of Conjunctive Queries with Negation |
EDBT
2002
ACM
14 years 7 months ago
2002
ACM
The problem of finding contained rewritings of queries using views is of great importance in mediated data integration systems. In this paper, we first present a general approach f...
DLOG
2008
13 years 10 months ago
2008
We have shown recently that, in extensions of ALC that involve inverse roles, conjunctive query answering is harder than satisfiability: it is 2-ExpTime-complete in general and NEx...
GEOINFORMATICA
2011
13 years 2 months ago
2011
Discovery of suitable web services is a crucial task in Spatial Data Infrastructures (SDI). In this work, we develop a novel approach to the discovery of geoprocessing services (WP...
FOCS
1998
IEEE
13 years 12 months ago
1998
IEEE
This paper deals with the evaluation of acyclic Boolean conjunctive queries in relational databases. By well-known results of Yannakakis [1981], this problem is solvable in polynom...
SAT
2004
Springer
14 years 1 months ago
2004
Springer
Kolaitis and Vardi pointed out that constraint satisfaction and conjunctive query containment are essentially the same problem. We study the Boolean conjunctive queries under a mor...