The double-assignment plant location problem with co-location

In this paper, a new variant of the Simple Plant Location Problem is proposed. We consider additional conditions in classic location-allocation problem for clients and facilities. Namely, some pairs have to be served by common plant. The resulting can addressed with existing models case single assignment. However, best our knowledge, proposed setting when each client must assigned couple facilities still unexplored. examine implications adding such constraints standard formulations SPLP double compare from theoretical point view. After that, we focus on study one models, which turned out set packing problem. All clique facets are identified separation algorithm devised. Although proved NP-hard, computational experience shows that effective efficient, reducing times duality gaps all instances tested.