In this paper, the problem of finding the minimum cost flow line able to produce different products is considered. This problem can be formulated as a shortest path problem on an acyclic di-graph when the machines graph associated with each product family is a chain or a comb. These graphs are relevant in production planning when dealing with pipelined assembly systems. We solve the problem usi...

Let N be a single-source single-sink ow network with n nodes, m arcs, and positive arc costs. We present a pseudo-polynomial algorithm that computes a maximum ow of minimum cost for N in time O(3=4 m p log n), where is the cost of the ow. This improves upon previously known methods for networks where the minimum cost of the ow is small. We also show an application of our ow algorithm to a well-...

Adler, I., A.J. Hoffman and R. Shamir, Monge and feasibility sequences in general flow problems, Discrete Applied Mathematics 44 (1993) 21-38. In a feasible transportation problem, there is always an ordering of the arcs such that greedily sending maximal flow on each arc in turn, according to that order, yields a feasible solution. We characterize those transportation graphs for which there ex...

Flow in planar graphs has been extensively studied, and very efficient algorithms have been developed to compute max-flows, min-cuts, and circulations. Intimate connections between solutions to the planar circulation problem and with "consistent" potential functions in the dual graph are shown. It is also shown that the set of integral circulations in a planar graph very naturally forms a distr...

information on the productivity, costs and applications of the logging system is a key component in the evaluation of management plans for the rehabilitation and utilization of caspian forests. skidding and road construction costs are expensive forest operations. determining the optimum forest road network density is one of the most important factors in sustainable forest management. logging me...

Periodic global updates of dual variables have been shown to yield a substantial speed advantage in implementations of push-relabel algorithms for the maximum flow and minimum cost flow problems. In this paper, we show that in the context of the bipartite matching and assignment problems, global updates yield a theoretical improvement as well. For bipartite matching, a pushrelabel algorithm tha...

An inverse optimization problems is defined as follows: Let S denote the set of feasible solutions of an optimization problem P, let c be a specified cost vector, and xO be a given feasible solution. We want to perturb the cost vector c to d so that x is an optimal solution of P with respect to the cost vector d , and lid clip is minimum, where 11.llp denotes some selected Lp norm. In this pape...

The current paper develops three different ways to measure the multi-period global cost efficiency for homogeneous networks of processes when the prices of exogenous inputs are known at all time periods. A multi-period network data envelopment analysis model is presented to measure the minimum cost of the network system based on the global production possibility set. We show that there is a rel...

Comparing word contexts is a key component of many NLP tasks, but rarely is it used in conjunction with additional ontological knowledge. One problem is that the amount of overhead required can be high. In this paper, we provide a graphical method which easily combines an ontology with contextual information. We take advantage of the intrinsic graphical structure of an ontology for representing...

nowadays, the environmental impact of transportation project and, especially air pollution impacts, are major concerns in evaluating transportation projects. based on this concern, beside definition of traditional objective functions like total travel time and total investment cost, different type of environmental related function is considered as objective function in urban network design. in...