{"title":"Logic-based benders decomposition methods for the distributed flexible job shop scheduling problem","authors":"Fuli Xiong, Hengchong Liu","doi":"10.1016/j.ejor.2025.08.039","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.08.039","url":null,"abstract":"The Distributed Flexible Job Shop Scheduling Problem (DFJSP) is a well-known <mml:math altimg=\"si1.svg\" display=\"inline\"><mml:mi mathvariant=\"script\">NP</mml:mi></mml:math>-hard optimization problem with widespread applications in production scheduling. It involves assigning jobs to factories, allocating operations to machines, and sequencing operations on each machine, which presents significant computational challenges. Although heuristic and metaheuristic approaches have been extensively studied, the exploration of exact algorithms for solving DFJSP remains limited. This paper addresses this gap by proposing three logic-based Benders decomposition (LBBD) frameworks specifically designed for the DFJSP, leveraging the problem’s decomposable structure to achieve optimal or near-optimal solutions with quantifiable quality guarantees within strict time limits. In each LBBD framework, the DFJSP is decomposed into a master problem and several subproblems based on specific decomposition schemes. The corresponding Mixed-Integer Linear Programming (MILP) models and Constraint programming (CP) models for these problems are formulated and solved alternately. Additionally, a hybrid optimization approach is developed by integrating LBBD with CP and heuristic search strategies. The proposed method includes an enhanced CP model with targeted improvements to boost its solving efficiency and incorporates a critical path-based local search strategy to further refine the solution quality. Moreover, several strong subproblem relaxation schemes are incorporated into the master problem under different LBBD frameworks. Comprehensive evaluations on an extended benchmark dataset containing 286 instances demonstrate that the hybrid algorithm achieves an average optimality gap of less than 1.2%. Compared to state-of-the-art MILP, CP, and heuristic methods, the proposed approach delivers superior solution quality and computational efficiency, establishing a new benchmark for solving the DFJSP.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"24 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Cost-sensitive single-index classification model","authors":"Jorge C-Rella , Ricardo Cao , Juan M. Vilar","doi":"10.1016/j.ejor.2025.08.058","DOIUrl":"10.1016/j.ejor.2025.08.058","url":null,"abstract":"<div><div>Single-index models (SIMs) are a type of semiparametric model in which a response variable is assumed to be related to a linear combination of explanatory variables by an unknown function, on which any restriction is imposed. Thus, they provide both interpretability and flexibility to capture complex data relationships. In this paper, SIMs are extended to the cost-sensitive classification problem by minimizing the different misclassification costs. The flexibility of SIMs combined with a cost-sensitive approach results in a powerful model to minimize losses and optimize decision making. This is demonstrated through an extensive simulation study and the analysis of five real data sets, where the proposed approach outperforms both parametric and semi-parametric previous approaches.</div></div>","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"328 1","pages":"Pages 295-308"},"PeriodicalIF":6.0,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Coordinated order scheduling and outsourcing on dedicated parallel machines","authors":"Jinwen Ou, Weidong Li, Xueling Zhong","doi":"10.1016/j.ejor.2025.08.035","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.08.035","url":null,"abstract":"In this paper we investigate two order scheduling problems with bundled operations on <mml:math altimg=\"si183.svg\" display=\"inline\"><mml:mi>m</mml:mi></mml:math> dedicated parallel machines when outsourcing is allowed. In the first problem, the objective is to minimize the makespan of the accepted jobs (orders) subject to the constraint that the total rejection (outsourcing) cost is no more than a budget. In the second problem, the objective is to minimize the makespan of accepted jobs plus the total rejection cost of rejected jobs. We show that the first problem cannot be approximated within a factor less than 2 in polynomial time, unless P = NP. For each of the two problems when <mml:math altimg=\"si183.svg\" display=\"inline\"><mml:mi>m</mml:mi></mml:math> is fixed, we present a quasi-linear-time FPTAS (fully polynomial time approximation scheme). For the second problem when <mml:math altimg=\"si3.svg\" display=\"inline\"><mml:mrow><mml:mi>m</mml:mi><mml:mo linebreak=\"goodbreak\" linebreakstyle=\"after\">=</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math>, we develop a faster FPTAS by an interesting problem transformation and advanced rounding method.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"14 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Optimistic and pessimistic approaches for cooperative games","authors":"Ata Atay , Christian Trudeau","doi":"10.1016/j.ejor.2025.09.002","DOIUrl":"10.1016/j.ejor.2025.09.002","url":null,"abstract":"<div><div>Cooperative game theory explores how to fairly allocate the joint value generated by a group of decision-makers, but its application is compromised by the large number of counterfactuals needed to compute the value of all coalitions, a problem made even more complicated when externalities are present. We provide a theoretical foundation for a simplification used in many applications, in which the value of a coalition is computed assuming that they either select before or after the complement set of agents, providing optimistic and pessimistic values on what a coalition should receive. In a vast set of problems exhibiting what we call feasibility externalities, we show that ensuring a coalition does not receive more than its optimistic value is always at least as difficult as ensuring it receives its pessimistic value. Furthermore, under the presence of negative externalities, we establish the existence of stable allocations that respect these bounds. Finally, we examine well-known optimization-based applications and their corresponding cooperative games to show how our results lead to new insights and allow the derivation of further results from the existing literature.</div></div>","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"328 2","pages":"Pages 725-733"},"PeriodicalIF":6.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Optimal area polygonisation problems: Mixed integer linear programming models","authors":"Hipólito Hernández-Pérez, Jorge Riera-Ledesma, Inmaculada Rodríguez-Martín, Juan-José Salazar-González","doi":"10.1016/j.ejor.2025.08.023","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.08.023","url":null,"abstract":"This paper describes approaches to finding polygons with maximum and minimum area through a given set of points on the Euclidean plane. Both problems are <mml:math altimg=\"si1.svg\" display=\"inline\"><mml:mi mathvariant=\"script\">NP</mml:mi></mml:math>-hard and of interest in Computational Geometry. They have been extensively studied, although only the recent literature presents mathematical formulations to consistently find optimal solutions to instances from a benchmark collection with up to 25 points. We present and compare eight new Mixed Integer Linear Programming models for the two problems. Four represent a polygon as a solution to the Asymmetric Travelling Salesman Problem, while the other four use the Symmetric Travelling Salesman Problem representation. Six of the models select triangles to compute the area of a polygon, while the other two models select subpolygons. A computational analysis on the benchmark collection shows that one of our new formulations can consistently solve most of the benchmark instances with up to 50 points. The success of our proposal is a linear system to select a triangulation of the point set, a partition of the triangulation to cover the internal and external area of a polygon, and a representation of the polygon as the solution of an Asymmetric Travelling Salesman Problem.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"53 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eric Ka Ho Leung, Sourav Das, Tolga Bektaş, Tsan-Ming Choi
{"title":"Optimizing delivery systems within the e-retail context: a weighted self-organizing map for delivery region partitioning","authors":"Eric Ka Ho Leung, Sourav Das, Tolga Bektaş, Tsan-Ming Choi","doi":"10.1016/j.ejor.2025.09.006","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.09.006","url":null,"abstract":"Today, e-tailing operations are well-established. However, managing dispersed same-day, next-day, or immediate deliveries remains a significant challenge. This necessitates refined vehicle routing and scheduling, which depends on efficient partitioning of the delivery regions. To tackle this, this paper develops a novel Weighted Self-Organizing Map Delivery Region Partitioning (WSOM-DRP) model that jointly generates delivery clusters and suggests optimal collection points for e-orders within each cluster. Using real data from a third-party logistics provider, our model is evaluated against alternative clustering methods (k-means, Ward hierarchical clustering, fuzzy c-means) using common clustering performance measures, travel distance and computation time. A comprehensive sensitivity analysis across varying cluster numbers confirms the model’s robustness, showing travel distance reduction of up to 36 % compared to the second-best method, particularly in high-density and high-traffic scenarios. Additionally, it yields significant improvements in clustering quality (e.g., a minimum of 15 % improvement in the silhouette index across scenarios) and an 18 % reduction in computation time compared to the next fastest benchmark. These findings highlight the practical value and adaptability of WSOM-DRP for optimizing delivery operations under diverse operational conditions and across different cluster granularities. The model also offers guidance on how to balance efficiency gains with operational complexity when selecting the number of clusters. By generating efficient delivery partitions and recommending optimal e-order collection locations during online checkout, our proposed WSOM-DRP model offers an e-commerce solution which is delivery efficient and cost-effective.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"315 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Benders decomposition for congested partial set covering location with uncertain demand","authors":"Alice Calamita, Ivana Ljubić, Laura Palagi","doi":"10.1016/j.ejor.2025.08.041","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.08.041","url":null,"abstract":"In this paper, we introduce a mixed integer quadratic formulation for the congested variant of the partial set covering location problem, which involves determining a subset of facility locations to open and efficiently allocating customers to these facilities to minimize the combined costs of facility opening and congestion while ensuring target coverage. To enhance the resilience of the solution against demand fluctuations, we address the case under uncertain customer demand using <mml:math altimg=\"si356.svg\" display=\"inline\"><mml:mi>Γ</mml:mi></mml:math>-robustness. We formulate the deterministic problem and its robust counterpart as mixed-integer quadratic problems. We investigate the effect of the protection level in adapted instances from the literature to provide critical insights into how sensitive the planning is to the protection level. Moreover, since the size of the robust counterpart grows with the number of customers, which could be significant in real-world contexts, we propose the use of Benders decomposition to effectively reduce the number of variables by projecting out of the master problem all the variables dependent on the number of customers. We illustrate how to incorporate our Benders approach within a mixed-integer second-order cone programming (MISOCP) solver, addressing explicitly all the ingredients that are instrumental for its success. We discuss single-tree and multi-tree approaches and introduce a perturbation technique to deal with the degeneracy of the Benders subproblem efficiently. Our tailored Benders approaches outperform the perspective reformulation solved using the state-of-the-art MISOCP solver Gurobi on adapted instances from the literature.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"35 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Strategic inventories under the reference price effect","authors":"Zeming Wang, Jasper Veldman, Ruud Teunter","doi":"10.1016/j.ejor.2025.08.060","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.08.060","url":null,"abstract":"Prior research shows that strategic inventories carried by a downstream retailer initially increase and then decrease the wholesale price. Carrying these inventories mitigates double marginalization and benefits the supplier and occasionally the retailer. Our study relaxes the assumption that customer purchasing decisions depend solely on the current price by recognizing that consumers react to price changes, known as the “reference price effect”. It investigates the interplay between strategic inventories and the reference price effect, with a focus on their impact on supply chain profitability. We develop a two-period game-theoretic model in which a supplier sells a new product through a retailer, competing to establish a reference price and manage strategic inventories. We find that the retailer only holds strategic inventories when the holding cost is sufficiently low. These inventories facilitate a high reference price, following the conventional wisdom that a high selling price deters strategic inventories and establishes a beneficial high reference price. However, under a sufficiently high holding cost, strategic inventories unexpectedly suppress first-period prices. This results in a novel outcome where firms set a low reference price, causing the supplier losses while the retailer profits. This contradicts existing studies, which suggest firms prefer a high reference price and that strategic inventories favor the supplier over the retailer, highlighting the need for managers to consider consumer responses to price changes. Our results remain robust under extensions with strategic consumers, decreasing product values, discounted future profits, and longer horizons.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"313 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mathijs Barkel, Rachael Colley, Maxence Delorme, David Manlove, William Pettersson
{"title":"Operational research approaches and mathematical models for kidney exchange: A literature survey and empirical evaluation","authors":"Mathijs Barkel, Rachael Colley, Maxence Delorme, David Manlove, William Pettersson","doi":"10.1016/j.ejor.2025.08.059","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.08.059","url":null,"abstract":"Kidney exchange is a transplant modality that has provided new opportunities for living kidney donation in many countries around the world since 1991. It has been extensively studied from an Operational Research (OR) perspective since 2004. This article provides a comprehensive literature survey on OR approaches to fundamental computational problems associated with kidney exchange over the last two decades. We also summarise the key integer linear programming (ILP) models for kidney exchange, showing how to model optimisation problems involving only cycles and chains separately. This allows new combined ILP models, not previously presented, to be obtained by amalgamating cycle and chain models. We present a comprehensive empirical evaluation involving all combined models from this paper in addition to bespoke software packages from the literature involving advanced techniques. This focuses primarily on computation times for 49 methods applied to 4320 problem instances of varying sizes that reflect the characteristics of real kidney exchange datasets, corresponding to over 200,000 algorithm executions. We have made our implementations of all cycle and chain models described in this paper, together with all instances used for the experiments, and a web application to visualise our experimental results, publicly available.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"38 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145059656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Soft regression trees: A model variant and a decomposition training algorithm","authors":"Antonio Consolo , Edoardo Amaldi , Andrea Manno","doi":"10.1016/j.ejor.2025.08.050","DOIUrl":"10.1016/j.ejor.2025.08.050","url":null,"abstract":"<div><div>Decision trees are widely used for classification and regression tasks in a variety of application fields due to their interpretability and good accuracy. During the past decade, growing attention has been devoted to globally optimized decision trees with deterministic or soft splitting rules at branch nodes, which are trained by optimizing the error function over all the tree parameters. In this work, we propose a new variant of soft multivariate regression trees (SRTs) where, for every input vector, the prediction is defined as the linear regression associated to a single leaf node, namely, the leaf node obtained by routing the input vector from the root along the branches with higher probability. SRTs exhibit the conditional computational property, i.e., each prediction depends on a small number of nodes (parameters), and our nonlinear optimization formulation for training them is amenable to decomposition. After showing a universal approximation result for SRTs, we present a decomposition training algorithm including a clustering-based initialization procedure and a heuristic for rerouting the input vectors along the tree. Under mild assumptions, we establish asymptotic convergence guarantees. Experiments on 15 well-known datasets indicate that our SRTs and decomposition algorithm yield higher accuracy and robustness compared with traditional soft regression trees trained using the nonlinear optimization formulation of Blanquero et al. (2021), and a significant reduction in training times as well as a slightly better average accuracy compared with the mixed-integer optimization approach of Bertsimas and Dunn (2019). We also report a comparison with the Random Forest ensemble method.</div></div>","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"328 2","pages":"Pages 607-619"},"PeriodicalIF":6.0,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145094128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}