Monire Jalili, Michael S. Pangburn, Euthemia Stavrulaki, Shubin Xu
{"title":"Sequential product launches with post-sale updates","authors":"Monire Jalili, Michael S. Pangburn, Euthemia Stavrulaki, Shubin Xu","doi":"10.1016/j.ejor.2025.01.018","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.01.018","url":null,"abstract":"As technology evolves, a seller may offer sequential releases of its product over time, with new versions offering superior performance. Beyond offering new product releases over time, sellers now increasingly have the option of offering post-sale software updates, thereby potentially extending product longevity. The potential to change product life cycles via software updates is of strategic importance, particularly since past and future product releases are interrelated. Considering stochastic technology evolution and strategic consumers, we study the strategy of augmenting paid product releases with free product updates. By contrasting this strategy against two benchmark product-launch policies without free updates, we show that offering free updates can generate nontrivial profit gains and optimally lengthen the seller’s new-product introduction cycles. We explore the sensitivity of the seller’s optimal release decisions and profit to key drivers, including costs and technology uncertainty. We also investigate the impact of consumer heterogeneity, distinct time-discount rates between the seller and consumers, and allowing multiple updates per product release. Our results show that while free updates ostensibly appear to favor consumers and do deliver utility to customers, they also are an effective mechanism for a seller to increase profits.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"3 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385313","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}
Mahdi Mostajabdaveh, F. Sibel Salman, Walter J. Gutjahr
{"title":"A branch-and-price algorithm for fast and equitable last-mile relief aid distribution","authors":"Mahdi Mostajabdaveh, F. Sibel Salman, Walter J. Gutjahr","doi":"10.1016/j.ejor.2025.01.032","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.01.032","url":null,"abstract":"The distribution of relief supplies to shelters is a critical aspect of post-disaster humanitarian logistics. In major disasters, prepositioned supplies often fall short of meeting all demands. We address the problem of planning vehicle routes from a distribution center to shelters while allocating limited relief supplies. To balance efficiency and equity, we formulate a bi-objective problem: minimizing a Gini-index-based measure of inequity in unsatisfied demand for fair distribution and minimizing total travel time for timely delivery. We propose a Mixed Integer Programming (MIP) model and use the <mml:math altimg=\"si1.svg\" display=\"inline\"><mml:mi>ϵ</mml:mi></mml:math>-constraint method to handle the bi-objective nature. By deriving mathematical properties of the optimal solution, we introduce valid inequalities and design an algorithm for optimal delivery allocations given feasible vehicle routes. A branch-and-price (B&P) algorithm is developed to solve the problem efficiently. Computational tests on realistic datasets from a past earthquake in Van, Turkey, and predicted data for Istanbul’s Kartal region show that the B&P algorithm significantly outperforms commercial MIP solvers.Our bi-objective approach reduces aid distribution inequity by 34% without compromising efficiency. Results indicate that when time constraints are very loose or tight, lexicographic optimization prioritizing demand coverage over fairness is effective. For moderately restrictive time constraints, a balanced approach is essential to avoid inequitable outcomes.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"27 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385312","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}
Mathieu Mercadier, Amine Tarazi, Paul Armand, Jean-Pierre Lardy
{"title":"Monitoring bank risk around the world using unsupervised learning","authors":"Mathieu Mercadier, Amine Tarazi, Paul Armand, Jean-Pierre Lardy","doi":"10.1016/j.ejor.2025.01.036","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.01.036","url":null,"abstract":"This paper provides a transparent and dynamic decision support tool that ranks clusters of listed banks worldwide by riskiness. It is designed to be flexible in updating and editing the values and quantities of banks, indicators, and clusters. For constructing this tool, a large set of stand-alone and systemic risk indicators are computed and reduced to fewer representative factors. These factors are set as features for an adjusted version of a nested k-means algorithm that handles missing data. This algorithm gathers banks per clusters of riskiness and ranks them. The results of the individual banks' multidimensional clustering are also aggregable per country and region, enabling the identification of areas of fragility. Empirically, we rank five clusters of 256 listed banks and compute 72 indicators, which are reduced to 12 components based on 10 main factors, over the 2004–2024 period. The findings emphasize the importance of giving special consideration to the ambiguous impact of banks' size on systemic risk measures.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"14 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077784","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}
Janaina F. Marchesi, Silvio Hamacher, Igor Tona Peres
{"title":"Stochastic model for physician staffing and scheduling in emergency departments with multiple treatment stages","authors":"Janaina F. Marchesi, Silvio Hamacher, Igor Tona Peres","doi":"10.1016/j.ejor.2025.01.027","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.01.027","url":null,"abstract":"We propose a new solution for the Emergency Department (ED) staffing and scheduling problem, considering uncertainty in patient arrival patterns, multiple treatment stages, and resource capacity. A two-stage stochastic mathematical programming model was developed. We employed a Sample Average Approximation (SAA) method to generate scenarios and a discrete event simulation to evaluate the results. The model was applied in a large hospital, with 72,988 medical encounters and 85 physicians in a ten-month period. Compared to the hospital’s actual scheduling, we obtained an overall average waiting time reduction from 54.6 (54.0–55.1) to 16.8 (16.7–17.0) minutes and an average Length of Stay reduction from 102.1 (101.7–102.4) to 64.3 (64.2–64.5) minutes. Therefore, this study offers a stochastic model that effectively addresses uncertainties in EDs, aligning physician schedules with patient arrivals and potentially improving the quality of service by reducing waiting times.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"61 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077785","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}
Stephanie Beyer Díaz, Kristof Coussement, Arno De Caigny
{"title":"From collaborative filtering to deep learning: Advancing recommender systems with longitudinal data in the financial services industry","authors":"Stephanie Beyer Díaz, Kristof Coussement, Arno De Caigny","doi":"10.1016/j.ejor.2025.01.022","DOIUrl":"10.1016/j.ejor.2025.01.022","url":null,"abstract":"<div><div>Recommender systems (RS) are highly relevant for multiple domains, allowing to construct personalized suggestions for consumers. Previous studies have strongly focused on collaborative filtering approaches, but the inclusion of longitudinal data (LD) has received limited attention. To address this gap, we investigate the impact of incorporating LD for recommendations, comparing traditional collaborative filtering approaches, multi-label classifier (MLC) algorithms, and a deep learning model (DL) in the form of gated recurrent units (GRU). Additional analysis for the best performing model is provided through SHapley Additive exPlanations (SHAP), to uncover relations between the different recommended products and features. Thus, this article contributes to operational research literature by (1) comparing several MLC techniques and RS, including state-of-the-art DL models in a real-life scenario, (2) the comparison of various featurization techniques to assess the impact of incorporating LD on MLC performance, (3) the evaluation of LD as sequential input through the use of DL models, (4) offering interpretable model insights to improve the understanding of RS with LD. The results uncover that DL models are capable of extracting information from longitudinal features for overall higher and statistically significant performance. Further, SHAP values reveal that LD has the higher impact on model output and managerial relevant temporal patterns emerge across product categories.</div></div>","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"323 2","pages":"Pages 609-625"},"PeriodicalIF":6.0,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077788","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}
Alessandro Agnetis , Mario Benini , Gaia Nicosia , Andrea Pacifici
{"title":"Trade-off between utility and fairness in two-agent single-machine scheduling","authors":"Alessandro Agnetis , Mario Benini , Gaia Nicosia , Andrea Pacifici","doi":"10.1016/j.ejor.2025.01.025","DOIUrl":"10.1016/j.ejor.2025.01.025","url":null,"abstract":"<div><div>We consider the problem arising when two agents, each owning a set of jobs, compete to schedule their jobs on a common processing resource. Each schedule implies a certain utility for each agent and an overall system utility. We are interested in solutions that incorporate some criterion of fairness for the agents and, at the same time, are satisfactory from the viewpoint of system utility. More precisely, we investigate the trade-off between fairness and system utility when both agents want to minimize the total completion time of their respective jobs. We analyze the structure of the set of such trade-off solutions, and propose an exact algorithm for their computation, based on the Lagrangian relaxation of a MILP formulation of the problem. A large set of computational experiments has been carried out to show the viability of the approach. Moreover, the results show that in most cases a solution having a high degree of fairness can be obtained by sacrificing a very limited amount of system utility.</div></div>","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"323 3","pages":"Pages 767-779"},"PeriodicalIF":6.0,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luciano Ferreira , Marcos Vinicius Milan Maciel , José Valério de Carvalho , Elsa Silva , Filipe Pereira Alvelos
{"title":"A new effective heuristic for the Prisoner Transportation Problem","authors":"Luciano Ferreira , Marcos Vinicius Milan Maciel , José Valério de Carvalho , Elsa Silva , Filipe Pereira Alvelos","doi":"10.1016/j.ejor.2025.01.029","DOIUrl":"10.1016/j.ejor.2025.01.029","url":null,"abstract":"<div><div>The Prisoner Transportation Problem is an NP-hard combinatorial problem and a complex variant of the Dial-a-Ride Problem. Given a set of requests for pick-up and delivery and a homogeneous fleet, it consists of assigning requests to vehicles to serve all requests, respecting the problem constraints such as route duration, capacity, ride time, time windows, multi-compartment assignment of conflicting prisoners and simultaneous services in order to optimize a given objective function.</div><div>In this paper, we present a new solution framework to address this problem that leads to an efficient heuristic. A comparison with computational results from previous papers shows that the heuristic is very competitive for some classes of benchmark instances from the literature and clearly superior in the remaining cases. Finally, suggestions for future studies are presented.</div></div>","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"323 3","pages":"Pages 753-766"},"PeriodicalIF":6.0,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077786","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":"Dynamic worker allocation in Seru production systems with actor–critic and pointer networks","authors":"Dongni Li, Hongbo Jin, Yaoxin Zhang","doi":"10.1016/j.ejor.2025.01.012","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.01.012","url":null,"abstract":"Following the rapid evolution of manufacturing industries, customer demands may change dramatically, which challenges the conventional production systems. <ce:italic>Seru</ce:italic> production system (SPS) is a key to deal with uncertain varieties and fluctuating volumes. In dynamic scenarios, orders with uncertain demands arrive over time. For each arriving order, appropriate workers should be allocated to assemble it. This study investigates the dynamic worker allocation problem with the objective of maximizing the revenue obtained by the SPS. To tackle this problem, a novel algorithm that integrates actor–critic and pointer networks is proposed. The global-and-local attention mechanism and twin focus encoders are particularly designed to address the dynamic and uncertain properties of the problem. The algorithm is compared to three approaches, including the standard actor–critic algorithm, proximal policy optimization algorithm, and the approximation algorithm with the best approximation ratio, in different scenarios, i.e., small, medium, and large factories. The proposed algorithm outperforms the standard actor–critic approach and proximal policy optimization algorithm, showing performance gaps ranging from 7.23% to 37.44%. It also outperforms the approximation algorithm, with gaps between 56.73% and 96.94%. Numerical results of the three scenarios show that the proposed algorithm is more efficient and effective in handling uncertainty and dynamics, making it a promising solution for real-world manufacturing production systems.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"38 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077790","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}
Diego Delle Donne, Alberto Santini, Claudia Archetti
{"title":"Integrating public transport in sustainable last-mile delivery: Column generation approaches","authors":"Diego Delle Donne, Alberto Santini, Claudia Archetti","doi":"10.1016/j.ejor.2024.12.047","DOIUrl":"https://doi.org/10.1016/j.ejor.2024.12.047","url":null,"abstract":"We tackle the problem of coordinating a three-echelon last-mile delivery system. In the first echelon, trucks transport parcels from distribution centres outside the city to public transport stops. In the second echelon, the parcels move on public transport and reach the city centre. In the third echelon, zero-emission vehicles pick up the parcels at public transport stops and deliver them to customers. We introduce two extended formulations for this problem. The first has two exponential sets of variables, while the second has one. We propose column generation algorithms and compare several methods to solve the pricing problems on specially constructed graphs. We also devise dual bounds, which we can compute even when the graphs are so large that not a single pricing round completes within the time limit. Compared to previous formulations, our models find 16 new best known solutions out of an existing dataset of 24 instances from the literature.","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"34 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077791","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 outbound shipment policy for an inventory system with advance demand information","authors":"Jana Ralfs, Dai T. Pham, Gudrun P. Kiesmüller","doi":"10.1016/j.ejor.2025.01.020","DOIUrl":"https://doi.org/10.1016/j.ejor.2025.01.020","url":null,"abstract":"This paper examines a single-echelon inventory system that fulfills stochastic orders from a production facility using a time-based shipment consolidation strategy. In this system, the production facility provides advance demand information to the warehouse, ensuring that all orders are placed with a positive demand lead time. Using value iteration, we identify the optimal outbound shipment quantities while accounting for costs related to early deliveries, late deliveries, and shipments. Additionally, this research highlights the impact of advance demand information on transportation capacity planning and the optimization of load factors","PeriodicalId":55161,"journal":{"name":"European Journal of Operational Research","volume":"16 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385314","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}