In pickup and delivery problems vehicles have to transport loads from origins to destinations without transshipment at intermediate locations. In this paper, we describe an algorithm to solve such problems. The algorithm is based on a set partitioning formulation of the problem and uses new column generation and branching schemes.

Traditional approach to the minimum length scheduling problem ignores the packet level details of transmission protocols, meaning that a packet transmission can be divided into several data chunks each of which is transmitted at different rate due to the difference in the set of concurrently transmitting nodes. This solution requires including packet headers for each data chunk resulting in bot...

A branch-and-cut-and-price algorithm for one-and two-dimensional two-staged cutting (stock) problems

We present a branch-and-price framework for solving the graph multicoloring problem. We propose column generation to implicitly optimize the linear programming relaxation of an independent set formulation (where there is one variable for each independent set in the graph) for graph multi-coloring. This approach, while requiring the solution of a difficult subproblem, is a promising method to ob...

In this paper, we present an exact solution procedure for the design of two-layer wavelength division multiplexing (WDM) optical networks with wavelength changers and bifurcated flows. This design problem closely resembles the traditional multicommodity flow problem, except that in the case of WDM optical networks, we are concerned with the routing of multiple commodities in two network layers....

In discrete optimization, most exact solution approaches are based on branch and bound, which is conceptually easy to parallelize in its simplest forms. More sophisticated variants, such as the so-called branch, cut, and price algorithms, are more difficult to parallelize because of the need to share large amounts of knowledge discovered during the search process. In the first part of the paper...

This paper presents a grid-enabled system for solving largescale optimization problems. The system has been developed using Globus and MPICH-G2 grid technologies, and consists of two BCP solvers and of an interface portal. After a brief introduction to Branch, Cut and Price optimization algorithms, the system architecture, the solvers and the portal user interface are described. Finally, some o...

In this paper we give an overview of the heuristics which are integrated into the open source branch-cut-and-price-framework SCIP. We briefly describe the fundamental ideas of different categories of heuristics and present some computational results which demonstrate the impact of heuristics on the overall solving process of SCIP.

In this chapter, we investigate the generalized assignment problem with the objective of finding a minimum-cost assignment of jobs to agents subject to capacity constraints. A complicating feature of the model is that the coefficients for resource consumption and capacity are random. The problem is formulated as a stochastic integer program with a penalty term associated with the violation of t...

Developing a branching scheme that is compatible with the column generation procedure can be challenging. Application specific and generic schemes have been proposed in the literature, but they have their drawbacks. One generic scheme is to implement standard branching in the space of the compact formulation to which the Dantzig-Wolfe reformulation was applied. However, in the presence of multi...