52 search results - page 6 / 11 » On the Decidability of Query Containment under Constraints |
PODS
1999
ACM
13 years 11 months ago
1999
ACM
Semistructured data occur in situations where information lacks a homogeneous structure and is incomplete. Yet, up to now the incompleteness of information has not been re ected b...
FOCS
2003
IEEE
14 years 20 days ago
2003
IEEE
We give a complexity theoretic classification of homomorphism problems for graphs and, more generally, relational structures obtained by restricting the left hand side structure ...
PODS
2009
ACM
14 years 8 months ago
2009
ACM
The paper investigates the question of whether a partially closed database has complete information to answer a query. In practice an enterprise often maintains master data Dm, a ...
VLDB
2006
ACM
14 years 7 months ago
2006
ACM
In this paper we study the following problem. Given a database and a set of queries, we want to find a set of views that can compute the answers to the queries, such that the amoun...
PODS
2005
ACM
14 years 7 months ago
2005
ACM
Owners of sources registered in an information integration system, which provides answers to a (potentially evolving) set of client queries, need to know their contribution to the...