We consider the problem of partitioning the nodes of a complete edge weighted graph into k clusters so as to minimize the sum of the diameters of the clusters. Since the problem is NP-complete, ourâ€¦ (More)

Support for exploratory interaction with databases in applications such as data mining requires that the first few results of an operation be available as quickly as possible. We study theâ€¦ (More)

Dominating sets in their many variations model a wealth of optimization problems like facility location or distributed le sharing. For instance, when a request can occur at any node in a graph andâ€¦ (More)

We study the trade-off between storage redundancy and access overhead for range queries, using the framework of [6]. We show that the Fibonacci workload of size n, which is the regular 2-dimensionalâ€¦ (More)

We consider problems of (new) station placement along (existing) railway tracks, so as to increase the number of users. We prove that, in spite of the NP-hardness for the general version, someâ€¦ (More)

Routing cars of trains for a given schedule is a problem that has been studied for a long time. The minimum number of cars to run a schedule can be found eÃ†ciently by means of ow algorithms.â€¦ (More)

Few concepts in ecology have been so influential as that of the trophic cascade. Since the 1980s, the term has been a central or major theme of more than 2000 scientific articles. Despite thisâ€¦ (More)

We consider a problem faced by train companies: How can trains be assigned to satisfy scheduled routes in a cost efficient way? Currently, many railway companies create solutions by hand, aâ€¦ (More)