European Journal of Operational Research最新文献

{"title":"[formula omitted]-Tree: Crossing sharp boundaries in regression trees to find neighbors","authors":"Xuecheng Tian, Shuaian Wang, Lu Zhen, Zuo-Jun (Max) Shen","doi":"10.1016/j.ejor.2025.02.031","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.031","url":null,"abstract":"Traditional classification and regression trees (CARTs) utilize a top-down, greedy approach to split the feature space into sharply defined, axis-aligned sub-regions (leaves). Each leaf treats all of the samples therein uniformly during the prediction process, leading to a constant predictor. Although this approach is well known for its interpretability and efficiency, it overlooks the complex local distributions within and across leaves. As the number of features increases, this limitation becomes more pronounced, often resulting in a concentration of samples near the boundaries of the leaves. Such clustering suggests that there is potential in identifying closer neighbors in adjacent leaves, a phenomenon that is unexplored in the literature. Our study addresses this gap by introducing the <mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree methodology, a novel method that extends the search for nearest neighbors beyond a single leaf to include adjacent leaves. This approach has two key innovations: (1) establishing an adjacency relationship between leaves across the tree space and (2) designing novel intra-leaf and inter-leaf distance metrics through an optimization lens, which are tailored to local data distributions within the tree. We explore three implementations of the <mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree methodology: (1) the Post-hoc <mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree (P<mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree), which integrates the <mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree methodology into constructed decision trees, (2) the Advanced <mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree, which seamlessly incorporates the <mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree methodology during the tree construction process, and (3) the P<mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-random forest, which integrates the P<mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree principles with the random forest framework. The results of empirical evaluations conducted on a variety of real-world and synthetic datasets demonstrate that the <mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree methods have greater prediction accuracy over the traditional models. These results highlight the potential of the <mml:math altimg=\"si545.svg\" display=\"inline\"><mml:mi>k</mml:mi></mml:math>-Tree methodology in enhancing predictive analytics by providing a deeper insight into the relationships between samples within the tree space.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"110 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583110","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":"Patient-to-room assignment with single-rooms entitlements: Combinatorial insights and integer programming formulations","authors":"Tabea Brandt, Christina Büsing, Felix Engelhardt","doi":"10.1016/j.ejor.2025.02.018","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.018","url":null,"abstract":"Patient-to-room assignment (PRA) is a scheduling problem in decision support for hospitals. It consists of assigning patients to rooms during their stay at a hospital according to certain conditions and objectives, e.g., ensuring gender separated rooms, avoiding transfers and respecting single-room requests. This work presents combinatorial insights about the feasibility of PRA and about how (many) single-room requests can be respected. We further compare different integer programming (IP) formulations for PRA as well as the influence of different objectives on the runtime using real-world data. Based on these results, we develop a fast IP-based solution approach, which obtains high quality solutions. In contrast to previous IP-formulations, the results of our computational study indicate that large, real-world instances can be solved to a high degree of optimality within (fractions of) seconds. We support this result by a computational study using a large set of realistic but randomly generated instances with 50% to 95% capacity utilisation.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"125 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641018","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":"Lagrangian relaxation and branch-and-price algorithm for resource assignment problem in divisional seru systems","authors":"Shiming Chen, Chengkuan Zeng, Yu Zhang, Jiafu Tang, Chongjun Yan","doi":"10.1016/j.ejor.2025.02.038","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.038","url":null,"abstract":"This paper addresses seru formation problem in divisional seru production system (SPS), which focuses on job-seru assignment, worker-seru assignment and operation-worker assignment in each seru. The problem is formulated as a mixed-integer nonlinear programming (MINLP) model with the objective of minimizing training and processing costs of workers. Once the job-seru assignment is determined, we employ a mixed-integer linear programming (MILP) model to describe worker-seru and operation-worker assignment in each seru. To tackle this challenge, we propose a two-phase approach to deal with this problem. In the first phase, we propose a Lagrangian relaxation algorithm to determine job-seru assignment, this approach can quickly compute the lower bound of the MILP by enumerating all possible job-seru assignments and eliminate unpromising ones. Subsequently, in the second phase, for each remaining job-seru assignment, we develop a branch-and-price algorithm to solve the MILP exactly. It is in the branch-and-bound framework, each node is solved by column generation (CG) algorithm. In CG, we apply a Dantzig Wolfe decompose to divide the original problem into a master problem and the pricing problems. A novel label-setting algorithm is employed based on the characteristics of the pricing problem. Additionally, we introduce effective acceleration strategies such as dominance rules and heuristic pricing. It facilitates the selection of the optimal job-seru assignment and obtains the optimal solution for the entire problem. Finally, extensive experiments validate the effectiveness and superiority of our proposed algorithm. We also discuss the impact of selected parameters on the cost and offer managerial insights.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"33 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641014","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":"Greedy Randomized Adaptive Search Procedures with Path Relinking. An analytical review of designs and implementations","authors":"Manuel Laguna, Rafael Martí, Anna Martínez-Gavara, Sergio Pérez-Peló, Mauricio G.C. Resende","doi":"10.1016/j.ejor.2025.02.022","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.022","url":null,"abstract":"This is a comprehensive review of the Greedy Randomized Adaptive Search Procedure (GRASP) metaheuristic and its hybridization with Path Relinking (PR). GRASP with PR has become a widely adopted approach for solving hard optimization problems since its proposal in 1999. The paper covers the historical development of GRASP with PR and its theoretical foundations, as well as recent advances in its implementation and application. The review includes a careful analysis of PR variants, paying special attention to memory-based and randomized designs, with a total of ten different implementations. It identifies the design questions that are still open in the scientific literature. The experimental section applies advanced PR implementations on two well-known combinatorial optimization problems, linear ordering and max-cut, in an effort to answer these open questions. The paper also explores the hybridization of PR and other metaheuristics, such as tabu search, scatter search, and random-keys genetic algorithms. Overall, this review provides valuable insights for researchers and practitioners seeking to implement GRASP with PR for solving optimization problems.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"49 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583111","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":"Randomized strategyproof mechanisms with best of both worlds fairness and efficiency","authors":"Ankang Sun, Bo Chen","doi":"10.1016/j.ejor.2025.02.027","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.027","url":null,"abstract":"We study the problem of mechanism design for allocating a set of indivisible items among agents with private preferences on items. We aim to design a mechanism that is strategyproof (in which agents find it optimal to report their true preferences) and ensures a certain level of fairness and efficiency. We first establish that no deterministic mechanism can simultaneously be strategyproof, fair, and efficient for the allocation of indivisible chores. We then introduce randomness to address this impossibility. For allocating indivisible chores, we propose randomized mechanisms that are strategyproof in expectation as well as ex-ante and ex-post (best of both worlds) fair and efficient. For allocating mixed items—where an item may be a good (positive utility) for one agent and a chore (negative utility) for another, we propose randomized mechanisms that are strategyproof in expectation while ensuring fairness and efficiency for two-agent scenarios.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"142 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583104","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":"Solving soft and hard-clustered vehicle routing problems: A bi-population collaborative memetic search approach","authors":"Yangming Zhou, Lingheng Liu, Una Benlic, Zhi-Chun Li, Qinghua Wu","doi":"10.1016/j.ejor.2025.02.021","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.021","url":null,"abstract":"The soft-clustered vehicle routing problem is a natural generalization of the classic capacitated vehicle routing problem, where the routing decision must respect the already taken clustering decisions. It is a relevant routing problem with numerous practical applications, such as packages or parcels delivery. Population-based evolutionary algorithms have already been adapted to solve this problem. However, they usually evolve a single population and suffer from early convergence especially for large instances, resulting in sub-optimal solutions. To maintain a high diversity so as to avoid premature convergence, this work proposes a bi-population collaborative memetic search method that adopts a bi-population structure to balance between exploration and exploitation, where two populations are evolved in a cooperative way. Starting from an initial population generated by a data-driven and knowledge-guided population initialization, two heterogeneous memetic searches are then performed by employing a pair of complementary crossovers (i.e., a multi-route edge assembly crossover and a group matching-based crossover) to generate offspring solutions, and a bilevel variable neighborhood search to explore the solution space at both cluster and customer levels. Once the two evolved new populations are obtained, a cooperative evolution mechanism is applied to obtain a new population. Extensive experiments on 404 benchmark instances show that the proposed algorithm significantly outperforms the current state-of-the-art algorithms. In particular, the proposed algorithm discovers new upper bounds for 16 out of the 26 large-sized benchmark instances, while matching the best-known solutions for the remaining 9 large-sized instances. Ablation experiments are conducted to verify the effectiveness of each key algorithmic module. Finally, the inherent generality of the proposed method is verified by applying it to the well-known (hard) clustered vehicle routing problem.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"2 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143532976","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":"An iterated local search algorithm for the traveling purchaser problem","authors":"Tomás Kapancioglu, Raquel Bernardino","doi":"10.1016/j.ejor.2025.02.024","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.024","url":null,"abstract":"The Traveling Purchaser Problem (TPP) is a generalization of the Traveling Salesman Problem (TSP) in which a list of items must be acquired by visiting a subset of markets. The objective is to minimize the total cost sustained along the route, including purchasing and traveling costs. Due to the NP-hard nature of the problem, solving the TPP in an exact manner is computationally challenging, implying the need for heuristic approaches to obtain quality solutions efficiently. This study proposes an algorithm based on the metaheuristic Iterated Local Search (ILS), complemented by a route configuration procedure that adjusts the subset of markets in the solution. The ILS is tested in benchmark instances, providing a performance comparison with other methods. The computational experiment for the asymmetric instances reveals the effectiveness and efficiency of the ILS, outperforming previously published results with statistical significance. Additional experiments are presented for the symmetric instances, pointing to the competitiveness and versatility of the ILS in relation to other heuristic approaches used in the literature.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"31 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143583109","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":"Platform acquisition in a triple-channel supply chain","authors":"Xiaoran Liu, Lusheng Shao, Xuwei Qin","doi":"10.1016/j.ejor.2025.02.033","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.033","url":null,"abstract":"Motivated by the observation that some online retail platforms begin to enter offline channels by acquiring traditional retailers, this paper studies the impact of platform acquisition in a context where a manufacturer sells a product via an online agency selling and two offline reselling channels. Considering three changes brought by platform acquisition in practice, namely, showrooming, “pay online but pickup in store (POPS)” and pricing power transfer effects, we investigate how platform acquisition impacts the firms’ pricing behaviors and profits, customer surpluses, and social welfare. Our analysis shows that, although acquisition may hurt the upstream manufacturer and the non-acquired traditional retailer, it always makes the platform and the acquired traditional retailer better off as a whole. Further, it may benefit the total supply chain and improve consumer surpluses and social welfare. Interestingly, platform acquisition leads to a demand siphon force (shifting demand from the non-acquired channel to the two channels related to acquisition) when platform acquisition brings strong showrooming and POPS effects; otherwise, it leads to the opposite demand spillover force. Finally, regarding the decision on the acquisition fee, there exists a moderate range that enables the platform and offline retailer to achieve a win-win situation. These findings collectively provide some valuable insights for decision-makers to understand the impacts of platform acquisition in a competitive triple-channel supply chain.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"90 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641017","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":"Streamlining emergency response: A K-adaptable model and a column-and-constraint-generation algorithm","authors":"Paula Weller, Fabricio Oliveira","doi":"10.1016/j.ejor.2025.02.016","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.016","url":null,"abstract":"Emergency response refers to the systematic response to an unexpected, disruptive occurrence such as a natural disaster. The response aims to mitigate the consequences of the occurrence by providing the affected region with the necessary supplies. A critical factor for a successful response is its timely execution, but the unpredictable nature of disasters often prevents quick reactionary measures. Preallocating the supplies before the disaster takes place allows for a faster response, but requires more overall resources because the time and place of the disaster are not yet known. This gives rise to a trade-off between how quickly a response plan is executed and how precisely it targets the affected areas. Aiming to capture the dynamics of this trade-off, we develop a <mml:math altimg=\"si345.svg\" display=\"inline\"><mml:mi>K</mml:mi></mml:math>-adjustable robust model, which allows a maximum of <mml:math altimg=\"si345.svg\" display=\"inline\"><mml:mi>K</mml:mi></mml:math> second-stage decisions, i.e., response plans. This mitigates tractability issues and allows the decision-maker to seamlessly navigate the gap between the readiness of a proactive yet rigid response and the accuracy of a reactive yet highly adjustable one. The approaches we consider to solve the <mml:math altimg=\"si345.svg\" display=\"inline\"><mml:mi>K</mml:mi></mml:math>-adaptable model are twofold: Via a branch-and-bound method as well as a static robust reformulation in combination with a column-and-constraint generation algorithm. In a computational study, we compare and contrast the different solution approaches and assess their potential.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"1 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143532975","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":"Endogenous directed technical change for energy transition","authors":"Younes Ben Zaied, Wided Mattoussi, Alessandro Marra","doi":"10.1016/j.ejor.2025.02.020","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.02.020","url":null,"abstract":"The finite nature of certain fossil fuels, which are essential inputs in production, imposes a substantial constraint on the economy's long-term growth potential. This paper develops an endogenous directed technical change model under uncertainty regarding the timing of a potential backstop technology discovery. The model directs R&amp;D towards increasing the probability of a technological breakthrough, triggering thereby a transition from a fossil fuel-dependent economy to one powered by cleaner, renewable energy sources. We derive analytical solutions using a general optimal control framework allowing to establish the Pontryagin (maximum principle) first-order optimality conditions, complemented with an adequate numerical assessment to a model of the optimal allocation of national economic resources between consumption, investment, and R&amp;D. We identify the optimal time paths for consumption in both the pre- and post-backstop adoption economies, the depletion rate of fossil fuels, investment in R&amp;D, and the utilization rate of the substitute, under two scenarios: when energy input and physical capital are substitutes in production, and when they are complements.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"6 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641015","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}