We present a new criterion space search algorithm, the balanced box method, for finding all nondominated points of a biobjectiveinteger program. The method extends the box algorithm, is easy to implement, and converg...
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We present a new criterion space search algorithm, the balanced box method, for finding all nondominated points of a biobjectiveinteger program. The method extends the box algorithm, is easy to implement, and converges quickly to the complete set of nondominated points. Because the method maintains, at any point in time, a diverse set of nondominated points, it is ideally suited for fast approximation of the efficient frontier. In addition, we present several enhancements of the well-known. epsilon-constraint, augmented weighted Tchebycheff, and perpendicular search methods. An extensive computational study, using instances from different classes of combinatorial optimization problems, demonstrates the efficacy of the balanced box method.
We conduct an in-depth analysis of the epsilon-constraint method (ECM) for finding the exact Pareto front for biobjective integer programming problems. We have found up to six possible different variants of the ECM. W...
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We conduct an in-depth analysis of the epsilon-constraint method (ECM) for finding the exact Pareto front for biobjective integer programming problems. We have found up to six possible different variants of the ECM. We first discuss the complexity of each of these variants and their relationship with other exact methods for solving biobjective integer programming problems. By extending some results of Neumayer and Schweigert (OR Spektrum 16: 267-276, 1994), we develop two variants of the ECM, both including an augmentation term and requiring N + 1 integer programs to be solved, where N is the number of nondominated points. In addition, we present another variant of the ECM, based on the use of elastic constraints and also including an augmentation term. This variant has the same complexity, namely N + 1, which is the minimum reached for any exact method. A comparison of the different variants is carried out on a set of biobjective location problems which we call p-median-cover problems;these include the objectives of the p-median and the maximal covering problems. As computational results show, for this class of problems, the augmented ECM with elastic constraint is the most effective variant for finding the Pareto front in an exact manner.
We propose an exact algorithm to find all nondominated points of biobjective integer programming problems, which arise in various applications of operations research. The algorithm is based on dividing objective space...
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We propose an exact algorithm to find all nondominated points of biobjective integer programming problems, which arise in various applications of operations research. The algorithm is based on dividing objective space into regions (boxes) and searching them by solving Pascoletti-Serafini scalarizations with fixed direction vector. We develop variants of the algorithm, where the choice of the scalarization model parameters differ; and demonstrate their performance through computational experiments both as exact algorithms and as solution approaches under time restriction. The results of our experiments show the satisfactory behaviour of our algorithm, especially with respect to the number of mixed integerprogramming problems solved compared to an existing approach. The experiments also demonstrate that different variants have advantages in different aspects: while some variants are quicker in finding the whole set of nondominated solutions, other variants return good-quality solutions in terms of representativeness when run under time restriction.
We propose an exact algorithm for solving biobjective integer programming problems, which arise in various applications of operations research. The algorithm is based on solving Pascoletti-Serafini scalarizations to s...
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We propose an exact algorithm for solving biobjective integer programming problems, which arise in various applications of operations research. The algorithm is based on solving Pascoletti-Serafini scalarizations to search specified regions (boxes) in the objective space and returns the set of nondominated points. We implement the algorithm with different strategies, where the choices of the scalarization model parameters and splitting rule differ. We then derive bounds on the number of scalarization models solved;and demonstrate the performances of the variants through computational experiments both as exact algorithms and as solution approaches under time restriction. The experiments demonstrate that different strategies have advantages in different aspects: while some are quicker in finding the whole set of nondominated solutions, others return good-quality solutions in terms of representativeness when run under time restriction. We also compare the proposed approach with existing algorithms. The results of our experiments show the satisfactory behaviour of our algorithm, especially when run under time limit, as it achieves better coverage of the whole frontier with a smaller number of solutions compared to the existing algorithms.
The pq-median problem, of Serra and ReVelle seeks to locate hierarchical facilities at two levels so as to obtain a coherent structure. Coherence requires that the entire area assigned to a facility at the inferior le...
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