We consider here a NP-hard problem related to the Routing and Wavelength Assignment (RWA) problem in optical networks, dealing with Scheduled Lightpath Demands (SLDs). An SLD is a connection demand between two nodes of the network, during a certain time. Given a set of SLDs, we want to assign a...

Given a finite set X and a collection Π, called a profile, of binary relations defined on X (which can be linear orders, complete preorders, any relations, and so on), a relation R is said to be median if it minimizes the total number of disagreements with respect to Π. In the context of...

Given a tournament T, Slater's problem consists in determining a linear order (i.e. a complete directed graph without directed cycles) at minimum distance from T, the distance between T and a linear order O being the number of directed edges with different orientations in T and in O. This paper...

Given a tournament T, a Banks winner of T is the first vertex of any maximal (with respect to inclusion) transitive subtournament of T. While Woeginger shows that recognizing whether a given vertex of T is a Banks winner is NP-complete, the computation of a Banks winner of T is polynomial, and...