19 search results - page 4 / 4 » On Preservation under Homomorphisms and Unions of Conjunctiv... |
ICDT
2012
ACM
11 years 7 months ago
2012
ACM
Previous studies of incomplete XML documents have identified three main sources of incompleteness – in structural information, data values, and labeling – and addressed data ...
PODS
2008
ACM
14 years 4 months ago
2008
ACM
We revisit the classical chase procedure, studying its properties as well as its applicability to standard database problems. We settle (in the negative) the open problem of decid...
WIDM
2005
ACM
13 years 10 months ago
2005
ACM
In XML retrieval, two distinct approaches have been established and pursued without much cross-fertilization taking place so far. On the one hand, native XML databases tailored to...
WISE
2005
Springer
13 years 10 months ago
2005
Springer
Abstract. Approximation has been identified as a potential way of reducing the complexity of logical reasoning. Here we explore approximation for speeding up instance retrieval in...