121 search results - page 20 / 25 » On Containment of Conjunctive Queries with Negation |
TALG
2010
13 years 6 months ago
2010
Fractional hypertree width is a hypergraph measure similar to tree width and hypertree width. Its algorithmic importance comes from the fact that, as shown in previous work [14], ...
ECAI
1994
Springer
13 years 11 months ago
1994
Springer
Abstract. Many recent works point out that there are several possibilities of assigning a meaning to a concept definition containing some sort of recursion. In this paper, we argue...
PODS
2007
ACM
14 years 7 months ago
2007
ACM
We show that relational algebra calculations for incomplete databases, probabilistic databases, bag semantics and whyprovenance are particular cases of the same general algorithms...
FOSSACS
2009
Springer
14 years 2 months ago
2009
Springer
Abstract. Graph logic (GL) is a spatial logic for querying graphs introduced by Cardelli et al. It has been observed that in terms of expressive power, this logic is a fragment of ...
VLDB
1995
ACM
13 years 11 months ago
1995
ACM
Scientific data of importance to biologists in the Humitn Genome Project resides not only in conventional da.tabases, but in structured files maintained in a number of different f...