This paper is devoted to the study of the reroute sequence planning problem in multi-protocol label switching networks from the polyhedral viewpoint. The reroute sequence plan polytope, defined as the convex hull of the incidence vectors of the reroute sequences which do not violate the network link capacities, is introduced and some of its properties … Read more
This paper is devoted to the approximate resolution of a strongly NP-hard resource-constrained scheduling problem which arises in relation to the operability of certain high availability real time distributed systems. We present an algorithm based on the simulated annealing metaheuristic and, building on previous research on exact resolution methods, extensive computational results demonstrating its practical … Read more
This paper is devoted to the study of a resource-constrained scheduling problem which arises in relation to the operability of certain high availability real-time distributed systems. After a brief survey of the literature, we prove the NP-hardness of the problem and exhibit a few polynomial special cases. We then present a branch-and-bound algorithm for the … Read more
This paper is devoted to the exact resolution of a strongly NP-hard resource-constrained scheduling problem, the Process Move Programming problem, which arises in relation to the operability of certain high availability real time distributed systems. Based on the study of the polytope defined as the convex hull of the incidence vectors of the admissible process … Read more
This paper presents a genetic algorithm for the Resource Constrained Project Scheduling Problem (RCPSP). The chromosome representation of the problem is based on random keys. The schedule is constructed using a heuristic priority rule in which the priorities of the activities are defined by the genetic algorithm. The heuristic generates parameterized active schedules. The approach … Read more
Several ‘tubechallenges’ have been attempted on the London Underground network, often gaining vast press coverage. The most famous of them consists of trying to travel to all 275 stations of the London Underground network (known as ‘the tube’) in the shortest possible time. In this article we examine how Operational Research can assist potential record-breakers, … Read more
We study a single-machine sequencing problem with both release dates and deadlines to minimize the total weighted completion time. We propose a branch-and-bound algorithm for this problem. The algorithm exploits an effective lower bound and a dynamic programming dominance technique. As a byproduct of the lower bound, we have developed a new algorithm for the … Read more
This paper presents a genetic algorithm for the Resource Constrained Multi-Project Scheduling Problem (RCMPSP). The chromosome representation of the problem is based on random keys. The schedules are constructed using a heuristic that builds parameterized active schedules based on priorities, delay times, and release dates defined by the genetic algorithm. The approach is tested on … Read more
This paper addresses the one-machine scheduling problem where the objective is to minimize a sum of costs such as earliness-tardiness costs. Since the sequencing problem is NP-hard, local search is very useful for finding good solutions. Unlike scheduling problems with regular cost functions, the scheduling (or timing) problem is not trivial when the sequence is … Read more
We consider the problem of scheduling hypermedia documents with elastic times. The objects have variable durations characterized by ideal, minimum, and maximum values. A schedule is a set of tensions on the arcs of the precedence graph which also represents synchronization constraints. We consider the problem of deciding if there exists a schedule in which … Read more