Given a point set P in the plane, the Delaunay graph with respect to axis-parallel rectangles is a graph defined on the vertex set P, whose two points p, q P are connected by an ...
This paper is motivated by the open question whether the union of two disjoint NPcomplete sets always is NP-complete. We discover that such unions retain much of the complexity of...
We investigate randomised algorithms for subset matching with spatial point sets—given two sets of d-dimensional points: a data set T consisting of n points and a pattern P consi...
We assume that safety of information stored in a database depends on the reliability of the agents who have performed the insertions in the database. We present a logic S to repres...
Laurence Cholvy, Robert Demolombe, Andrew J. I. Jo...
In this paper we propose a new bottom-up query evaluation method for stratified deductive databases based on the Magic Set approach. As the Magic Sets rewriting may lead to unstra...