Ontologies can be used to provide an enriched vocabulary for the formulation of queries over instance data. We identify query emptiness and predicate emptiness as two central reas...
Franz Baader, Meghyn Bienvenu, Carsten Lutz, Frank...
In order to answer efficiently range queries in 2-d R-trees, first we sort queries by means of a space filling curve, then we group them together, and finally pass them for process...
Existing distributed publish/subscribe systems (DPSS) offer loosely coupled and easy to deploy content-based stream delivery services to a large number of users. However, the lack ...
We address the problem of answering conjunctive queries over knowledge bases, specified by sets of first-order sentences called tuple-generating dependencies (TGDs). This problem i...
This paper presents a difference calculus for determining changes to rule conditions in an active DBMS. The calculus has been used for implementing an algorithm to efficiently mon...