In this paper we propose a new procedure for classification based on a hybrid approach. The classification problem is solved by minimizing the distance between the components of each clusters and the centers of the cl...
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The problem is related to the operation of a fleet of aircraft with a certain flying program in which making the availability of the aircraft sufficient to meet the flying program is a challenging issue. During the pr...
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ISBN:
(纸本)9780976348665
The problem is related to the operation of a fleet of aircraft with a certain flying program in which making the availability of the aircraft sufficient to meet the flying program is a challenging issue. During the pre- or after-flight inspections, some component failures of the aircraft(s) may be found. In such cases, the aircraft(s) are sent to the repair shop to be scheduled as maintenance jobs, consisting of failure repairs or preventive maintenance tasks. The objective is to schedule the jobs in such a way that sufficient number of aircraft is available for the next flight programs. The main resource, as well as the main constraint, in the shop is skilled-workforce. The problem is formulated as a mixed-integer mathematical programming model in which the network flow structure is used to compute the skilled-workforce requirements.
Cutting plane methods are widely used for solving convex optimization problems and are of fundamental importance, e.g., to provide tight bounds for mixed-integer Programs (MIPs). This is obtained by embedding a cut-se...
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ISBN:
(纸本)9783642135194
Cutting plane methods are widely used for solving convex optimization problems and are of fundamental importance, e.g., to provide tight bounds for mixed-integer Programs (MIPs). This is obtained by embedding a cut-separation module within a search scheme. The importance of a sound search scheme is well known in the Constraint programming (CP) community. Unfortunately, the "standard" search scheme typically used for MIP problems, known as the Kelley method, is often quite unsatisfactory because of saturation issues. In this paper we address the so-called Lift-and-Project closure for 0-1 MIPs associated with all disjunctive cuts generated from a given set of elementary disjunction. We focus on the search scheme embedding the generated cuts. In particular, we analyze a general meta-scheme for cutting plane algorithms, called in-out search, that was recently proposed by Ben-Ameur and Neto [1]. Computational results on test instances from the literature are presented, showing that using a more clever meta-scheme on top of a black-box cut generator may lead to a significant improvement.
Discrete support vector machines (DSVM) are recently introduced classifiers that might be preferable to the standard support vector machine due to a more appropriate modeling of classification errors. However, this ad...
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ISBN:
(纸本)9783642010439
Discrete support vector machines (DSVM) are recently introduced classifiers that might be preferable to the standard support vector machine due to a more appropriate modeling of classification errors. However, this advantage comes at the cost of an increased computational effort. In particular, DSVM rely upon a mixed-integer program, whose optimal solution is prohibitively expensive to obtain. Therefore, heuristics are needed to construct respective classifiers. This paper proposes a novel heuristic incorporating recent advances from the field of integerprogramming and demonstrates its effectiveness by means of empirical experimentation. Furthermore, the appropriateness of the DSVM formulation is examined to shed light on the degree of agreement between the classification aim and its implementation in form of a mathematical program.
Gomory's mixed-integer Cuts (GMICs) are widely used in modern branch-and-cut codes for the solution of mixed-integer Programs. Typically, GMICs are iteratively generated from the optimal basis of the current Linea...
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ISBN:
(纸本)9783642135194
Gomory's mixed-integer Cuts (GMICs) are widely used in modern branch-and-cut codes for the solution of mixed-integer Programs. Typically, GMICs are iteratively generated from the optimal basis of the current Linear programming (LP) relaxation, and immediately added to the LP before the next round of cuts is generated. Unfortunately, this approach prone to instability. In this paper we analyze a different scheme for the generation of rank-1 GMIC read from a basis of the original LP-the one before the addition of any cut. We adopt a relax-and-cut approach where the generated GMIC are not added to the current LP, but immediately relaxed in a Lagrangian fashion. Various elaborations of the basic idea are presented, that lead to very fast-yet accurate-variants of the basic scheme. Very encouraging computational results are presented, with a comparison with alternative techniques from the literature also aimed at improving the GMIC quality, including those proposed very recently by Balas and Bonami and by Dash and Goycoolea.
In this study, we establish a parallel between two classes of pricing problems that have attracted the attention of researchers in marketing, theoretical computer science and operations research, each community addres...
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In this study, we establish a parallel between two classes of pricing problems that have attracted the attention of researchers in marketing, theoretical computer science and operations research, each community addressing issues from its own vantage point. More precisely, we contrast the problems of pricing a network or a product line, in order to achieve maximum revenue, given that customers maximize their individual utility. Throughout the article, we focus on problems that can be formulated as mixed-integer programs.
This paper explores mathematical programming models for an exam timetabling problem related to Kuwait University (KU). In particular, we consider two subproblems: (a) the ExamTimetabling Problem (ETP), which is concer...
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This paper explores mathematical programming models for an exam timetabling problem related to Kuwait University (KU). In particular, we consider two subproblems: (a) the ExamTimetabling Problem (ETP), which is concerned with assigning exams to designated exam-periods and classrooms, and (b) the Proctor Assignment Problem (PAP), which deals with the assignment of proctors to exams. While this exam timetabling problem is ubiquitous in many academic institutions worldwide, idiosyncrasies of the problem related to gender-based policies and having multiple exam centers at KU require novel models. A mixed-integer exam timetabling programming model (ETM) is developed for ETP, which takes into account restrictions related to exam-period conflicts, facility and human resources, and commuting and traffic considerations. Assuming that exam-periods are specified for all exams as determined by ETM, another mixed-integer programming model is formulated for PAP, denoted by PAM, which incorporates the proctors' preferences for specific days and exam-periods. Computational results are reported and analyzed for solving ETM and PAM directly using the CPLEX Optimization Software (version 9.0), and for implementing a specialized sequential LP-based heuristic for solving PAM. The results obtained significantly improve upon those derived via the existing manual approach implemented at KU, in terms of eliminating conflicts as well as from the overall efficiency and equity points of view.
In this paper, we propose a link outage probability based resource allocation scheme for multi-radio multi-channel wireless mesh networks. The objective is to optimize the link outage probability under the effect of c...
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ISBN:
(纸本)9781424456383
In this paper, we propose a link outage probability based resource allocation scheme for multi-radio multi-channel wireless mesh networks. The objective is to optimize the link outage probability under the effect of channel variation and external interference while preserving the end-to-end traffic demand requirements. The problem is formulated as a mixed-integer nonlinear programming problem, which is solved by decomposing it into a feasibility-checking problem and an outage probability search problem so that the original problem can be solved iteratively with reduced complexity. Numerical results are provided to show that the proposed algorithm is superior to the existing scheme in reducing the outage probability.
The development of optimization models for planning and scheduling is one of the most useful tools for improving productivity of a large number of manufacturing companies. This paper presents a mixed-integer programmi...
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The development of optimization models for planning and scheduling is one of the most useful tools for improving productivity of a large number of manufacturing companies. This paper presents a mixed-integer programming model for scheduling steelmaking-continuous casting production. We first review the recent works in continuous casting planning. We focus on a model inspired from an application of steelmaking-continuous casting by Arcelor Group in Liege, Belgium. The process scheduling is characterized by several constraints: job grouping, technological interdependence, no dead time inside the same group of jobs and dynamic processing time of jobs. We present a formulation with mixed-integer linear programming which can be solved using standard software packages. Finally, we treat a few examples to illustrate this application and we conclude this paper with some comments and directions for future extensions. (c) 2004 Elsevier B.V. All rights reserved.
The design of telecommunication network concerns the selection of arcs in a graph with involved cost as low as possible, but satisfies constraints such as point-to-point demands routed across the network, arc capacity...
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The design of telecommunication network concerns the selection of arcs in a graph with involved cost as low as possible, but satisfies constraints such as point-to-point demands routed across the network, arc capacity, hop constraints and so on. Such a design must allocate enough flows and diverse routing paths through the network to ensure that feasible information flows continue to exist, even when components of the network fail. In this paper, we propose a reliable mathematical model to optimally design a minimum-cost survivable telecommunication network that continues to support a good communication under any node failure scenario.
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