Diagrams are ubiquitous in economics and are uncontestably among the most used, if not the most important workhorses of economists, though they come in many forms. This essay examines the different uses of graphs and diagrams in the pioneering work of two Victorian economists, Stanley Jevons and...

The generalized truck-and-trailer routing problem (GTTRP) constitutes a uni¯ed model for vehicle routing problems with trailers and a fixed lorry-trailer assignment. The GTTRP is a generalization of the truck-and-trailer routing problem (TTRP), which itself is an extension of the well-known...

Publish/subscribe systems are getting more and more integrated into the execution of business processes in process aware information systems. This integration enables the distribution of the process logic and increases the scalability and adaptability of the process enactment infrastructure. A...

A network is robust to the extent that it is not vulnerable to disconnection by removal of nodes. The minimum number of nodes that need be removed to disconnect a pair of other nodes is called the connectivity of the pair. It can be proved that the connectivity is also equal to the number of...

We study the maximum weighted independent-set problem on interval graphs with uncertainty on the vertex weights. We use the absolute robustness criterion and the min-max regret criterion to evaluate solutions. For a discrete scenario set, we fi nd that the problem is NP-hard for each of the...

We examine the interrelationships between a large number of commodity series over a 20 year period through the use of minimum spanning trees. We find that there are several distinct clusters, that these are reasonably stable over time, and that the degree of interlinkage is time varying

We investigate the daily correlation present among market indices of stock exchanges located all over the world in the time period Jan 1996 - Jul 2009. We discover that the correlation among market indices presents both a fast and a slow dynamics. The slow dynamics reflects the development and...

Two hypotheses concerning the acquisition of network graph structures were tested. Strong support was found for the hypothesis that the deep structure of a graph affects how quickly it will be learned. Specifically, scale-free graphs were acquired more readily than random graphs. Much less...