In this paper we describe the extreme points of two closely related polytopes that are assigned to a digraph. The first polytope is the set of all sharing vectors (elements from the unit simplex) such that each node gets at least as much as each of its successors. The second one is the set of...

Many economic and social situations can be represented by a digraph. Both axiomatic and iterativemethods to determine the strength or power of all the nodes in a digraph have been proposed inthe literature. We propose a new method, where the power of a node is determined by both thenumber of its...

The problem studied in this paper consists in optimizing the refueling costs of a fleet of locomotives over a railway network. The goal consists in determining the number of trucks contracted for each yard and to determine the refueling plan of each locomotive, while minimizing the costs and...