In this paper we present the results of an investigation of the possib
ilities offered by three well-known metaheuristic algorithms to solve
the timetable problem, a multi-constrained, NP-hard, combinatorial opt
imization problem with real-world applications. First, we present our
model of the problem, including the definition of a hierarchical struc
ture for the objective function, and of the neighborhood search operat
ors which we apply to matrices representing timetables. Then we report
about the outcomes of the utilization of the implemented systems to t
he specific case of the generation of a school timetable. We compare t
he results obtained by simulated annealing, tabu search and two versio
ns, with and without local search, of the genetic algorithm. Our resul
ts show that GA with local search and tabu search based on temporary p
roblem relaxations both outperform simulated annealing and handmade ti
metables.