For some $$\beta \ge 1/2$$ , a $$\varDelta _{\beta }$$ -metric graph $$G=(V,E,w)$$ is complete edge-weighted such that $$w(v,v)=0$$ $$w(u,v)=w(v,u)$$ and $$w(u,v) \le \beta \cdot (w(u,x)+w(x,v))$$ for all vertices $$u,v,x\in V$$ . A $$H=(V', E')$$ called spanning subgraph of $$G=(V, E)$$ if $$V'=V$$ $$E'\subseteq E$$ Given positive integer p, let H be G satisfying the three conditions: (i) ther...

0377-2217/$ see front matter 2011 Elsevier B.V. A doi:10.1016/j.ejor.2011.01.014 ⇑ Tel.: +90 312 290 27 68; fax: +90 312 266 40 54. E-mail address: [email protected] In this paper, we study allocation strategies and their effects on total routing costs in hub networks. Given a set of nodes with pairwise traffic demands, the p-hub median problem is the problem of choosing p nodes as hub loca...

In telecommunication and transportation systems, the uncapacitated multiple allocation hub location problem (UMAHLP) arises when we must flow commodities or information between several origin–destination pairs. Instead of establishing a direct node to node connection from an origin to its destination, the flows are concentrated with others at facilities called hubs. These flows are transported ...

Hub networks have always been acriticalissue in locating health facilities. Recently, a study has been investigated by Cocking et al. (2006)in Nouna health district in Burkina Faso, Africa, with a population of approximately 275,000 people living in 290 villages served by 23 health facilities. The travel times of the population to health services become extremely high during the rainy season, s...

Given a metric graph G = (V,E,w) and a positive integer k, the Single Allocation k-Hub Center problem is to find a spanning subgraph H of G such that (i) C ⊂ V is a clique of size k in H; (ii) V \ C forms an independent set in H; (iii) each v ∈ V \C is adjacent to exactly one vertex in C; and (iv) the diameter D(H) is minimized. The vertices selected in C are called hubs and the rest of vertice...

New formulation and a branch-and-cut algorithm for the multiple allocation p-hub median problem Sergio García, Mercedes Landete and Alfredo Marín Septiembre 2011 ISSN 1576-7264 Depósito legal A-646-2000 Abstract This article deals with the uncapacitated multiple allocation phub median problem, where p facilities (hubs) must be located among n available sites in order to minimize the transportat...

The hub location problem deals with finding the location of hub facilities and allocating the demand nodes to these hub facilities so as to effectively route the demand between any origin–destination pair. In the extensive literature on this challenging network design problem, it has widely been assumed that the subgraph induced by the hub nodes is complete. Relaxation of this basic assumption ...