Florence Mendes

An exact method for graph coloring

We are interested in the graph coloring problem. We propose an exact method based on a linear-decomposition of the graph. The complexity of this method is exponential according to the linearwidth of the entry graph, but linear according to its number of vertices. We present some experiments performed on literature instances, among which COLOR02 library instances. Our method is useful to solve more quickly than other exact algorithms instances with small linearwidth, such as mug graphs. Moreover, our algorithms are the first to our knowledge to solve the COLOR02 instance 4-Inser_3 with an exact method.

Tabu Search to Plan Schedules in a Multiskill Customer Contact Center

We have studied a realistic case of scheduling problem in a customer contact center, dealing with multiskill agents. Our model combines the last two steps of the standard approach by determining shifts and by assigning them to agents at the same time (scheduling and rostering). Moreover, we have considered realistic vacations, according to legal constraints and preferences of agents. We have envisioned entire weeks of work, with variable meal times and meal durations, without overtime. In this paper, we define the problem and describe a Tabu search based solution

Pre-processing and Linear-Decomposition Algorithm to Solve the k-Colorability Problem

We are interested in the graph coloring problem. We studied the effectiveness of some pre-processings that are specific to the k-colorability problem and that promise to reduce the size or the difficulty of the instances. We propose to apply on the reduced graph an exact method based on a linear-decomposition of the graph. We present some experiments performed on literature instances, among which DIMACS library instances.