Hubs are high-degree nodes within a network, ubiquitous in complex networks such as telecommunication, biological, social and semantic networks. Here, we do not seek hub that is single node, but consisting of k nodes. Formally, given graph G=(V,E), set A⊆V size induces connected subgraph from which at least p edges emanate. Thus, identify can act unit (due to the connectivity constraint) cut co...

In this paper, some distributed approximation algorithms for uncapacitated facility location problem and fault-tolerant facility location problem are summarized, respectively. The worst-case run time of the distributed version of the uncapacitated facility location problem is ( ) O n , where n is the number of network nodes. In addition, the approximation approach for the fault-tolerant facilit...

In this paper, we investigate in the application of the Contract Net negotiation Protocol (CNP) to deal with a dynamic hard transportation problems. Our interest in the Multi-agent negotiation approaches accounts for its proved suitability with dynamic and uncertain domains [8][9]. We address the resolution of the uncapacitated-multi-vehicle-Dynamic Pickup and Delivery Problem with Time Windows...

We consider an extension of the dynamic uncapacitated lot-sizing problem to account for co-production, where multiple products are produced simultaneously in a single production run. We formulate the problem as a mixed-integer linear programming problem. We then show that a variant of the well-known zero-inventory property holds for this problem, and use this property to extend a dynamic progra...

hub location-allocation problems are currently a subject of keen interest in the research community. however, when this issue is considered in practice, significant difficulties such as traffic, commodity transportation and telecommunication tend to be overlooked. in this paper, a novel robust mathematical model for a p-hub covering problem, which tackles the intrinsic uncertainty of some param...

We consider a supply chain setting where multiple uncapacitated facilities serve a set of customers with a single product. The majority of literature on such problems requires assigning all of any given customer’s demand to a single facility. While this single-sourcing strategy is optimal under linear (or concave) cost structures, it will often be suboptimal under the nonlinear costs that arise...

In this paper we consider a well-known class of valid inequalities for the p-median and the uncapacitated facility location polytopes, the odd cycle inequalities. It is known that their separation problem is polynomially solvable. We give a new polynomial separation algorithm based on a reduction from the original graph. Then, we define a non-trivial class of graphs, where the odd cycle inequal...

This paper presents a study on reliable single and multiple allocation hub-and-spoke network design problems where disruptions at hubs and the resulting hub unavailability can be mitigated by backup hubs and alternative routes. It builds nonlinear mixed integer programming models and presents linearized formulas. To solve those difficult problems, Lagrangian relaxation and Branch-and-Bound meth...