GRASP strategies for a bi-objective commercial territory design problem

A bi-objective commercial territory design problem motivated by a real-world application from the bottled beverage distribution industry is addressed. The problem considers territory compactness and balancing with respect to number of customers as optimization criteria. Previous work has focused on exact methods for small- to medium-scale instances. In this work, a GRASP framework is proposed for tackling considerably large instances. Within this framework two general schemes are developed. For each of these schemes two strategies are studied: (i) keeping connectivity as a hard constraint during construction and post-processing phases and, (ii) ignoring connectivity during the construction phase and adding this as another minimizing objective function during the post-processing phase. These strategies are empirically evaluated and compared to NSGA-II, one of the most successful evolutionary methods known in literature. Computational results show the superiority of the proposed strategies. In addition, one of the proposed GRASP strategies is successfully applied to a case study from industry.