We address a bilevel location problem where a leader first decides which facilities to open and their access prices; then, customers make individual decisions minimizing individual costs. In this note we prove that, when access costs do not fulfill metric properties, the problem is NP-hard even if facilities can be opened at no fixed cost.
Citation
Università degli Studi dell'Aquila Dipartimento di Ingegneria/Scienze dell'Informazione e Matematica, via Vetoio, 67010 Coppito, L'Aquila, Italy April 2016