204 search results - page 1 / 41 » Containment of Conjunctive Queries with Negation: Algorithms... |
DEXA
2010
Springer
13 years 4 months ago
2010
Springer
We consider the containment problem for conjunctive queries with atomic negation. Firstly, we refine an existing algorithm based on homomorphism checks, which itself improves other...
ICDT
2007
ACM
13 years 10 months ago
2007
ACM
Query containment is a fundamental problem of databases. Given two queries q1 and q2, it asks whether the set of answers to q1 is included in the set of answers to q2 for any datab...
ADBIS
2009
Springer
13 years 11 months ago
2009
Springer
Abstract. We consider the problem of query containment for conjunctive queries with the safe negation property. Some necessary conditions for this problem are given. A part of the ...
ERSHOV
2009
Springer
13 years 11 months ago
2009
Springer
Abstract. We consider the problem of query containment for conjunctive queries with safe negation property. A necessary and sufficient condition for two queries to be in containmen...
EDBT
2004
ACM
14 years 4 months ago
2004
ACM
We study the problem of answering queries over sources with limited access patterns. The problem is to decide whether a given query Q is feasible, i.e., equivalent to an executable...