In traditional multi-commodity flow theory, the task is to send a certain amount of each commodity from its start to its target node, subject to capacity constraints on the edges. However, no restriction is imposed on the number of paths used for delivering each commodity; it is thus feasible to spread the flow over a large number of different paths. Motivated by routing problems arising in rea...

Article history: Received 10 August 2012 Received in revised format 14 September 2012 Accepted September 27 2012 Available online 28 September 2012 The hub location problem involves a network of origins and destinations over which transportation takes place. There are many studies associated with finding the location of hub nodes and the allocation of demand nodes to these located hub nodes to ...

The capacitated arc routing problem (CARP) is one of the most important routing problems with many applications in real world situations. In some real applications such as urban waste collection and etc., decision makers have to consider more than one objective and investigate the problem under uncertain situations where required edges have demand for more than one type of commodity. So, in thi...

We propose a syntax-semantics interface that realises the mapping between syntax and semantics as a relation and does not make functionality assumptions in either direction. This interface is stated in terms of Extensible Dependency Grammar (XDG), a grammar formalism we newly specify. XDG’s constraint-based parser supports the concurrent flow of information between any two levels of linguistic ...

We discuss the student scheduling problem as it generally applies to high-schools in North-America. We show that the problem is NP-hard and discuss various variations to its formulation. We focus on multi-commodity flow problems because there has recently been much work and a number of interesting results on approximates solutions to such problems.

ENABLING PEER-TO-PEER SWARMING FOR MULTI-COMMODITY DISSEMINATION

The understanding of the performance and design of national networks with rerouting is now well ad­ vanced. In particular, simple and robust dynamic routing strategies, and sympathetic dimensioning procedures, have been developed. However, the extension of this understanding to international net­ works requires consideration of a number of new issues. An important example concerns the partition...

We define a NP-hard clustered variant of the Set Covering Problem where subsets are partitioned into K clusters and a fixed cost is paid for selecting at least one subset in a given cluster. This variant can reformulate as a master problem various multi-commodity flow problems in transportation planning. We show that the problem is approximable within ratio (1+2)(e/e−1)H(q), where q is the maxi...

In logistics management, selecting the carriers to deliver freight is a critical process for global enterprises. This paper determines the optimal carrier selection based on a multi-commodity reliability criterion for a logistics network subject to budget. Traditionally, a logistics network includes nodes and routes connecting the supplier and customer. Along each route, several carriers are av...

The line planning problem is one of the fundamental problems in strategic planning of public and rail transport. It consists in finding lines and corresponding frequencies in a network such that a given demand can be satisfied. There are two objectives. Passengers want to minimize travel times, the transport company wishes to minimize operating costs. We investigate three variants of a multi-co...