No abstract

In this paper we address the problem of locating a new facility on a d-dimensional space when the distance measure (ℓp-or polyhedral-norms) is different at each one of the sides of a given hyperplane H. We relate this problem with the physical phenomenon of refraction, and extends it to any finite dimension space and different distances at each one of the sides of any hyperplane. An application to this problem is the location of a facility within or outside an urban area where different distance measures must be used. We provide a new second order cone programming formulation, based on the ℓp-norm representation given in [3] that allows to solve, exactly, the problem in any finite dimension space with semidefinite programming tools. We also extend the problem to the case where the hyperplane is considered as a rapid transit media (a different third norm is also considered over H) that allows the demand to travel faster through H to reach the new facility. Extensive computational experiments run in Gurobi are reported in order to show the effectiveness of the approach.Date: April 11, 2018. 2010 Mathematics Subject Classification. 90B85, 90C22, 90C30, 47A30.

The discrete ordered median problem (DOMP) is formulated as a set-partitioning problem using an exponential number of variables. Each variable corresponds to a set of demand points allocated to the same facility with the information of the sorting position of their corresponding costs. We develop a column generation approach to solve the continuous relaxation of this model. Then we apply a branch-price-and-cut algorithm to solve small- to large-sized instances of DOMP in competitive computational time.

No abstract