A Greedy Randomized Adaptive Search Procedure for Technicians and Interventions Scheduling for Telecommunications

The subject of the 5th challenge proposed by the French Society of Operations Research and Decision Analysis (ROADEF) consists in scheduling technicians and interventions for telecommunications (see http://www.g-scop.inpg.fr/ChallengeROADEF2007/ or http://www.roadef.org/). The aim of this problem is to assign interventions to teams of technicians. Each intervention has a given priority and the objective is to minimize z = 28t1+14t2+4t3+ t4 where tλ is the ending time of the last scheduled intervention of priority λ. A schedule is subjected to the following constraints: (1) a team should not change during one day, (2) two interventions assigned on the same day to the same team are done at different times, (3) all predecessors have to be completed before starting an intervention, (4) the working days have a limited duration Hmax and (5) to work on an intervention, a team has to meet the requirements. Let us note that it is allowed to hire an intervention to an external company but the total amount of cost for hired interventions cannot exceed a given budget A. It is easy to show that this problem belongs to the family of NP-hard problems.