Let $G$ be a bipartite graph. In this paper we consider the two kind of location problems namely $p$-center and $p$-median problems on bipartite graphs. The $p$-center and $p$-median problems asks to find a subset of vertices of cardinality $p$, so that respectively the maximum and sum of the distances from this set to all other vertices in $G$ is minimized. For each case we present some proper...

The p-median problem is central to much of discrete location modeling and theory. While the p-median problem is NP-hard on a general graph, it can be solved in polynomial time on a tree. A linear time algorithm for the 1-median problem on a tree is described. We also present a classical formulation of the problem. Basic construction and improvement algorithms are outlined. Results from the lite...

We deal, from a theoretical point of view, with the asymmetric Hamiltonian p–median problem. This problem, which has many applications, can be viewed as a mixed routing location problem. An ILP-formulation based on a new class of inequalities (subtour number constraints) is presented. The associated Hamiltonian p–median polytope is examined, in particular its dimension and its affine hull. We d...

in this paper, a robust model presented is developed for hub covering flow problem in which hubs have capacity. this problem has two objective functions converting to a single-objective problem by using weighting method. firstly, the problem will be formulated in a certain case. then, by considering the demand as a non-random variable, it will be modeled by robust optimization. finally, by usin...

This work approaches the P-median problem with a partitioning around medoids methodology. This problem has been extensively studied because of the multiple applications and its NP-hard nature; therefore several are the efforts to find optimal solutions. In this paper we consider two case studies: 1) instances from OR-Library and 2) geographical objects from the metropolitan zone of Toluca, Mexi...

in this paper, a hierarchical p-hub median problem is considered that all the nodes and arcs on the network have limited capacities. proposed model has three-level where the complete network at the top level consists of the central hubs. the second and third levels consist of hub and demand nodes respectively, which are connected through star networks. also, delivery time restriction is taken i...