Patrick G. McKeown

A tabu search heuristic procedure for the fixed charge transportation problem

Abstract We develop a tabu search approach for the fixed charge transportation (FCT) problem using recency based and frequency based memories, together with two strategies for each of the intermediate and long term memory processes, making use of a network based implementation of the simplex method as the local search method. Our approach is evaluated computationally on randomly generated problems of different sizes and of different ranges of magnitude of fixed costs relative to variable costs. Comparisons are made with two leading methods previously proposed, one in the category of exact methods and one in the category of heuristic methods. Our tabu search procedure obtains optimal or near-optimal solutions more than a thousand times faster than the exact solution algorithm for simple problems, and thoroughly dominates the exact algorithm on all dimensions for more complex problems. Compared to the heuristic approach, on very small and easy test problems the tabu search procedure required about the same amount of solution time and found solutions at least as good. However, for larger problems and for problems with higher fixed relative to variable costs, the tabu search procedure was 3–4 times faster than the competing heuristic, and found significantly better solutions in all cases.

Tabu search applied to the general fixed charge problem

Recent successes in applying tabu search to a wide variety of classical optimization problems have motivated the investigation of applying tabu search to the well-known general fixed charge problem (GFCP). In this paper, an adaptation of tabu search to GFCP is described and computational results are given. In addition, the computational results are compared with those obtained from SWIFT-2, the most well-known and frequently used heuristic method for GFCP. As will be shown, the results are very encouraging.

Manheim auctions: transforming interorganizational relationships with an extranet

This case study demonstrates how a traditional face-to-face auction has been augmented by an electronic sales system to draw on the advantages of an extranet (lower site specificity, less risk, more information, just-in-time buying, lower costs). The paper suggests adoption strategies for an extranet and describes how to assess a disintermediation threat. It explains that an extranet is a device for redesigning interorganizational structures and provides further evidence of the ongoing creative destruction of existing business practices caused by Internet technologies.

On solving the continuous data editing problem

Abstract The data editing problem is concerned with identifying the most likely source of errors in computerized data bases. Given a record that is known to fail one or more ological consistency edits, the objective is to determine the minimum (possibly weighted) number of fields that could be changed in order to correct the record. While this problem can easily be formulated as a pure fixed-charge problem, it can be extremely difficult to solve under certain data conditions. In this paper we show how a number of structural characteristics in this problem can be exploited to dramatically reduce the computational time required to solve particularly difficult data edition problems.

An algorithm for solving fixed-charge problems using surrogate constraints

Abstract In recent years, many researchers have shown that surrogate constraints can be used to reduce the computational requirements of integer and mixed-integer programming problems. In this paper, we develop an algorithm that uses surrogate constraints io solve fixed-charge problems. This algorithm generates a candidate solution for the fixed-charge problem by solving a set covering problem. If the candidate solution is infeasible in the fixed-charge problem a surrogate constraint is generated and added to the set covering problem to cut this solution from the feasible region. This process is repeated until a feasible solution to the fixed-charge problem is found. This solution is then used as an incumbent solution in a branch-and-bound procedure, which solves the problem to optimality. In those cases where the problem has only fixed-charges, the optimal solution can be found without the branch-and-bound procedure. Computational results for various types of problems are given. These results indicate that this algorithm tends to perform better than existing branch-and-bound solution procedures.

Some computational results of using the Ahrens--Finke method for handling degeneracy in fixed charge transportation problems

In a recent paper, Ahrens and Finke present a procedure for resolving degeneracy in the fixed cost transportation problem by perturbing the supplies and demands. This paper presents computational results of using that procedure in both vertex ranking and branch-and-bound algorithms for the fixed charge transportation problems as compared to using previously available methods for resolving degeneracy in those algorithms.

Topologies for Electronic Cooperation

Electronic commerce is generally considered to be the use of communication networks, such as the Internet, to facilitate cooperation between buyers and sellers (e.g., Kalakota and Whinston, 1996). In this paper, we argue that a broader perspective is more appropriate and that electronic commerce should be seen as a general form of cooperation within an organization and between an organization and its stakeholders. As a result, we distinguish between three types of communication networks (see Table 1), based on whether the intent of the network is to support cooperation with a range of stakeholders, cooperation among employees, or cooperation with a business partner. We briefly describe each of these topologies and then elaborate on how they can be used to support cooperation.

Using Linear Programming to Find Approximate Solutions to the Fields to Impute Problem for Industry Data

Sande has suggested a mathematical programming formulation of the fields to impute problem (FTIP) for continuous data. This formulation seeks to find a minimum weighted sum of fields that would need to be changed to yield an acceptable record by solving a mixed integer programming problem known as the fixed charge problem. While this formulation can and has been solved to find an optimal solution to the FTIP, this approach can be expensive in terms of solution time. In this paper, we demonstrate the use of a heuristic procedure to find an approximately optimal solution to FTIP. This procedure uses the SWIFT algorithm developed by Walker in conjunction with a judicious choice of dummy variable costs to arrive at an approximate solution based on a linear programming solution. We will show that this solution is optimal in many cases. We will also discuss the use of the special structure of FTIP to arrive at an optimal solution to the LP problem.

LPMPS: A student oriented preprocessor for MPS/360

Abstract Even though linear programming is one of the most widely taught and used management science techniques, the commercial LP computer packages are not extensively used in the classroom. This is due to their cumbersome data input and control language requirements. This paper describes a student oriented FORTRAN preprocessor, LPMPS, that facilitates the use of one of these large scale packages, IBMs MPS/360. The use and implementation of LPMPS are discussed and compared with the use of MPS/360.