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In recent years, a wide range of techniques has been developed to predict electoral results and to measure the influence of different factors in these results. In this paper, we analyze the influence of the political profile of candidates (characterized by personal and political features) and their campaign effort (characterized by electoral expenditure and by territorial deployment strategies retrieved from social networks activity) on the electoral results. This analysis is carried out by using three of the most frequent data analyitcs algorithms in the literature. For our analysis, we consider the 2017 Parliamentary elections in Chile, which are the first elections after a major reform of the electoral system, that encompassed a transition from a binomial to a proportional system, a modification of the districts’ structure, an increase in the number of seats, and the requirement of gender parity in the lists of the different coalitions. The obtained results reveal that, regardless of the political coalition, the electoral experience of candidates, in particular in the same seat they are running for (even when the corresponding district is modified), is by large the most influential factor to explain the electoral results. However, the attained results show that the influence of other features, such as campaign expenditures, depends on the political coalition. Additionally, by means of a simulation procedure, we show how different levels of territorial deployment efforts might impact on the results of candidates. This procedure could be used by parties and coalitions when planning their campaign strategies.
Camilo Campos-Valdés; Eduardo Álvarez-Miranda; Mauricio Morales Quiroga; Jordi Pereira; Félix Liberona Durán. The Impact of Candidates’ Profile and Campaign Decisions in Electoral Results: A Data Analytics Approach. Mathematics 2021, 9, 902 .
AMA StyleCamilo Campos-Valdés, Eduardo Álvarez-Miranda, Mauricio Morales Quiroga, Jordi Pereira, Félix Liberona Durán. The Impact of Candidates’ Profile and Campaign Decisions in Electoral Results: A Data Analytics Approach. Mathematics. 2021; 9 (8):902.
Chicago/Turabian StyleCamilo Campos-Valdés; Eduardo Álvarez-Miranda; Mauricio Morales Quiroga; Jordi Pereira; Félix Liberona Durán. 2021. "The Impact of Candidates’ Profile and Campaign Decisions in Electoral Results: A Data Analytics Approach." Mathematics 9, no. 8: 902.
Battarra et al. recently proposed a novel assembly line balancing problem with applications to the apparel industry, where the tasks are performed in a fixed order. To solve the problem, one has to assign workers and tasks to the workstations with the objective of maximising the throughput of the assembly line. In this paper, we provide dynamic programming formulations for the general problem and some special cases. We then use these formulations to develop an exact solution approach that optimally solves the instances in Battarra et al. within seconds.
Jordi Pereira; Marcus Ritt. A note on “Algorithms for the Calzedonia workload allocation problem”. Journal of the Operational Research Society 2021, 1 -4.
AMA StyleJordi Pereira, Marcus Ritt. A note on “Algorithms for the Calzedonia workload allocation problem”. Journal of the Operational Research Society. 2021; ():1-4.
Chicago/Turabian StyleJordi Pereira; Marcus Ritt. 2021. "A note on “Algorithms for the Calzedonia workload allocation problem”." Journal of the Operational Research Society , no. : 1-4.
The flowtime network restoration problem was introduced by Averbakh and Pereira (2012) who presented a Minimum Spanning Tree (MST) heuristic, two local search procedures, and an exact branch-and-bound (B&B) algorithm. This note corrects the computational results in Averbakh and Pereira (2012).
Yaarit Miriam Cohen; Pinar Keskinocak; Jordi Pereira. A note on the flowtime network restoration problem. IISE Transactions 2021, 1 -2.
AMA StyleYaarit Miriam Cohen, Pinar Keskinocak, Jordi Pereira. A note on the flowtime network restoration problem. IISE Transactions. 2021; ():1-2.
Chicago/Turabian StyleYaarit Miriam Cohen; Pinar Keskinocak; Jordi Pereira. 2021. "A note on the flowtime network restoration problem." IISE Transactions , no. : 1-2.
We consider a recently introduced class of network construction problems where edges of a transportation network need to be constructed by a server (construction crew). The server has a constant construction speed which is much lower than its travel speed, so relocation times are negligible with respect to construction times. It is required to find a construction schedule that minimizes a non-decreasing function of the times when various connections of interest become operational. Most problems of this class are strongly NP-hard on general networks, but are often tree-efficient, that is, polynomially solvable on trees. We develop a generic local search heuristic approach and two metaheuristics (Iterated Local Search and Tabu Search) for solving tree-efficient network construction problems on general networks, and explore them computationally. Results of computational experiments indicate that the methods have excellent performance.
Igor Averbakh; Jordi Pereira. Tree optimization based heuristics and metaheuristics in network construction problems. Computers & Operations Research 2020, 128, 105190 .
AMA StyleIgor Averbakh, Jordi Pereira. Tree optimization based heuristics and metaheuristics in network construction problems. Computers & Operations Research. 2020; 128 ():105190.
Chicago/Turabian StyleIgor Averbakh; Jordi Pereira. 2020. "Tree optimization based heuristics and metaheuristics in network construction problems." Computers & Operations Research 128, no. : 105190.
The simple assembly line balancing problem (SALBP) considers work division among different workstations of a serially arranged assembly process to maximise its efficiency under workload (cumulative) and technological (precedence) constraints. In this work, we consider a variant of the SALBP which allows parallel workstations. To study the effect of parallel stations, we propose a new problem (the parallel station assembly line balancing problem or PSALBP) in which the objective is to minimise the number of parallel stations required to obtain the maximum theoretical efficiency of the assembly process. We study the complexity of the problem and identify a polynomially solvable case. This result is then used as a building block for the development of a heuristic solution procedure. Finally, we carry out a computational experiment to identify the characteristics of assembly lines that may benefit from station paralleling and to evaluate the performance of the proposed heuristic.
Eduardo Álvarez-Miranda; Sebastián Chace; Jordi Pereira. Assembly line balancing with parallel workstations. International Journal of Production Research 2020, 1 -21.
AMA StyleEduardo Álvarez-Miranda, Sebastián Chace, Jordi Pereira. Assembly line balancing with parallel workstations. International Journal of Production Research. 2020; ():1-21.
Chicago/Turabian StyleEduardo Álvarez-Miranda; Sebastián Chace; Jordi Pereira. 2020. "Assembly line balancing with parallel workstations." International Journal of Production Research , no. : 1-21.
Electoral systems are modified by individuals who have incentives to bias the rules for their political advantage (i.e., gerrymandering). To prevent gerrymandering, legislative institutions can rely on mathematical tools to guarantee democratic fairness and territorial contiguity. These tools have been successfully used in the past; however, there is a need to accommodate additional meanings of the term fairness within the electoral systems of modern democracies. In this paper, we present an optimization framework that considers multiple criteria for drawing districts and assigning the number of representatives. Besides some typical districting criteria (malapportionment and contiguity), we introduce novel criteria for ensuring territorial equilibrium and incentives for candidates to deploy their representation efforts fairly during their campaign and period in office. We test the method, which we denote as Multi-criteria Pen, in a recent and a forthcoming reform of the Chilean electoral system. The results show the potential of our tool to improve the current territorial design and offers insights on the motivations, objectives, and deficiencies of both reform plans.
Eduardo Álvarez-Miranda; Camilo Campos-Valdés; Maurcio Morales Quiroga; Matías Moreno-Faguett; Jordi Pereira. A Multi-Criteria Pen for Drawing Fair Districts: When Democratic and Demographic Fairness Matter. Mathematics 2020, 8, 1404 .
AMA StyleEduardo Álvarez-Miranda, Camilo Campos-Valdés, Maurcio Morales Quiroga, Matías Moreno-Faguett, Jordi Pereira. A Multi-Criteria Pen for Drawing Fair Districts: When Democratic and Demographic Fairness Matter. Mathematics. 2020; 8 (9):1404.
Chicago/Turabian StyleEduardo Álvarez-Miranda; Camilo Campos-Valdés; Maurcio Morales Quiroga; Matías Moreno-Faguett; Jordi Pereira. 2020. "A Multi-Criteria Pen for Drawing Fair Districts: When Democratic and Demographic Fairness Matter." Mathematics 8, no. 9: 1404.
We address the problem of finding an arborescence of minimum total edge weight rooted at a given vertex in a directed, edge-weighted graph. If the arborescence must span all vertices the problem is solvable in polynomial time, but the non-spanning version is NP-hard. We propose reduction rules which determine vertices that are required or can be excluded from optimal solutions, a modification of Edmonds algorithm to construct arborescences that span a given set of selected vertices, and embed this procedure into an iterated local search for good vertex selections. Moreover, we propose a cutset-based integer linear programming formulation, provide different linear relaxations to reduce the number of variables in the model and solve the reduced model using a branch-and-cut approach. We give extensive computational results showing that both the heuristic and the exact methods are effective and obtain better solutions on instances from the literature than existing approaches, often in much less time.
Marcus Ritt; Jordi Pereira. Heuristic and exact algorithms for minimum-weight non-spanning arborescences. European Journal of Operational Research 2020, 287, 61 -75.
AMA StyleMarcus Ritt, Jordi Pereira. Heuristic and exact algorithms for minimum-weight non-spanning arborescences. European Journal of Operational Research. 2020; 287 (1):61-75.
Chicago/Turabian StyleMarcus Ritt; Jordi Pereira. 2020. "Heuristic and exact algorithms for minimum-weight non-spanning arborescences." European Journal of Operational Research 287, no. 1: 61-75.
In this work, we focus on general multi-objective scheduling problems that can be modeled using a Petri net framework. Due to their generality, Petri nets are a useful abstraction that captures multiple characteristics of real-life processes. To provide a general solution procedure for the abstraction, we propose three alternative approaches using an indirect scheme to represent the solution: (1) a genetic algorithm that combines two objectives through a weighted fitness function, (2) a non dominated sorting genetic algorithm (NSGA-II) that explicitly addresses the multi-objective nature of the problem and (3) a multi-objective local search approach that simultaneously explores multiple candidate solutions. These algorithms are tested in an extensive computational experiment showing the applicability of this general framework to obtain quality solutions.
Gonzalo Mejía; Jordi Pereira. Multiobjective scheduling algorithm for flexible manufacturing systems with Petri nets. Journal of Manufacturing Systems 2020, 54, 272 -284.
AMA StyleGonzalo Mejía, Jordi Pereira. Multiobjective scheduling algorithm for flexible manufacturing systems with Petri nets. Journal of Manufacturing Systems. 2020; 54 ():272-284.
Chicago/Turabian StyleGonzalo Mejía; Jordi Pereira. 2020. "Multiobjective scheduling algorithm for flexible manufacturing systems with Petri nets." Journal of Manufacturing Systems 54, no. : 272-284.
In this paper, we consider a parallel machine scheduling problem in which machines have a limited workload capacity and jobs have deadlines and release dates. The problem is motivated by the operation of energy storage management systems for microgrids under emergency conditions and generalizes some problems that have already been studied in the literature for their theoretical value. In this work, we propose heuristic and exact algorithms to solve the problem. The heuristics are adaptations of classical bin packing heuristics in which additional conditions on the feasibility of a solution are imposed, whereas the exact method is a branch-and-price approach. The results show that the branch-and-price approach is able to optimally solve random instances with up to 250 jobs within a time limit of one hour, while the heuristic procedures provide near optimal solution within reduced running times. Finally, we also provide additional complexity results for a special case of the problem.
Luis Osorio-Valenzuela; Jordi Pereira; Franco Quezada; Óscar C. Vásquez. Minimizing the number of machines with limited workload capacity for scheduling jobs with interval constraints. Applied Mathematical Modelling 2019, 74, 512 -527.
AMA StyleLuis Osorio-Valenzuela, Jordi Pereira, Franco Quezada, Óscar C. Vásquez. Minimizing the number of machines with limited workload capacity for scheduling jobs with interval constraints. Applied Mathematical Modelling. 2019; 74 ():512-527.
Chicago/Turabian StyleLuis Osorio-Valenzuela; Jordi Pereira; Franco Quezada; Óscar C. Vásquez. 2019. "Minimizing the number of machines with limited workload capacity for scheduling jobs with interval constraints." Applied Mathematical Modelling 74, no. : 512-527.
Assembly line balancing is a family of combinatorial optimization problems that has been widely studied in the literature due to its simplicity and industrial applicability. Most line balancing problems are NP-hard as they subsume the bin packing problem as a special case. Nevertheless, it is common in the line balancing literature to cite [A. Gutjahr and G. Nemhauser, An algorithm for the line balancing problem, Management Science 11 (1964) 308-315] in order to assess the computational complexity of the problem. Such an assessment is not correct since the work of Gutjahr and Nemhauser predates the concept of NP-hardness. This work points at over 50 publications since 1995 with the aforesaid error.
Eduardo Álvarez-Miranda; Jordi Pereira. On the complexity of assembly line balancing problems. Computers & Operations Research 2019, 108, 182 -186.
AMA StyleEduardo Álvarez-Miranda, Jordi Pereira. On the complexity of assembly line balancing problems. Computers & Operations Research. 2019; 108 ():182-186.
Chicago/Turabian StyleEduardo Álvarez-Miranda; Jordi Pereira. 2019. "On the complexity of assembly line balancing problems." Computers & Operations Research 108, no. : 182-186.
A network is given whose edges need to be constructed (or restored after a disaster). The lengths of edges represent the required construction/restoration times given available resources, and one unit of length of the network can be constructed per unit of time. All points of the network are accessible for construction at any time. For each pair of vertices, a due date is given. It is required to find a construction schedule that minimizes the maximum lateness of all pairs of vertices, where the lateness of a pair is the difference between the time when the pair becomes connected by an already constructed path and the pair’s due date. We introduce the problem and analyze its structural properties, present a mixed-integer linear programming formulation, develop a number of lower bounds that are integrated in a branch-and-bound algorithm, and discuss results of computational experiments both for instances based on randomly generated networks and for instances based on 2010 Chilean earthquake data.The online appendix is available at https://doi.org/10.1287/ijoc.2017.0796.
Igor Averbakh; Jordi Pereira. Lateness Minimization in Pairwise Connectivity Restoration Problems. INFORMS Journal on Computing 2018, 30, 522 -538.
AMA StyleIgor Averbakh, Jordi Pereira. Lateness Minimization in Pairwise Connectivity Restoration Problems. INFORMS Journal on Computing. 2018; 30 (3):522-538.
Chicago/Turabian StyleIgor Averbakh; Jordi Pereira. 2018. "Lateness Minimization in Pairwise Connectivity Restoration Problems." INFORMS Journal on Computing 30, no. 3: 522-538.
In order to minimize costs, manufacturing companies have been relying on assembly lines for the mass production of commodity goods. Among other issues, the successful operation of an assembly line requires balancing work among the stations of the line in order to maximize its efficiency, a problem known in the literature as the assembly line balancing problem, ALBP. In this work, we consider an ALBP in which task assignment and equipment decisions are jointly considered, a problem that has been denoted as the robotic ALBP. Moreover, we focus on the case in which equipment has different costs, leading to a cost-oriented formulation. In order to solve the problem, which we denote as the cost-oriented robotic assembly line balancing problem, cRALBP, a hybrid metaheuristic is proposed. The metaheuristic embeds results obtained for two special cases of the problem within a genetic algorithm in order to obtain a memetic algorithm, applicable to the general problem. An extensive computational experiment shows the advantages of the hybrid approach and how each of the components of the algorithm contributes to the overall ability of the method to obtain good solutions.
Jordi Pereira; Marcus Ritt; Óscar C. Vásquez. A memetic algorithm for the cost-oriented robotic assembly line balancing problem. Computers & Operations Research 2018, 99, 249 -261.
AMA StyleJordi Pereira, Marcus Ritt, Óscar C. Vásquez. A memetic algorithm for the cost-oriented robotic assembly line balancing problem. Computers & Operations Research. 2018; 99 ():249-261.
Chicago/Turabian StyleJordi Pereira; Marcus Ritt; Óscar C. Vásquez. 2018. "A memetic algorithm for the cost-oriented robotic assembly line balancing problem." Computers & Operations Research 99, no. : 249-261.
Jordi Pereira; Eduardo Álvarez-Miranda. An exact approach for the robust assembly line balancing problem. Omega 2018, 78, 85 -98.
AMA StyleJordi Pereira, Eduardo Álvarez-Miranda. An exact approach for the robust assembly line balancing problem. Omega. 2018; 78 ():85-98.
Chicago/Turabian StyleJordi Pereira; Eduardo Álvarez-Miranda. 2018. "An exact approach for the robust assembly line balancing problem." Omega 78, no. : 85-98.
A line balancing problem considers the assignment of operations to workstations in an assembly line. While assembly lines are usually associated to mass production of standardised goods, their advantages have led to their widespread use whenever a product-oriented production system is applicable and the benefits of the labour division and specialisation are significant, even when some of its characteristics may deviate from classical assembly lines. In this work, we study a line balancing problem found in the textile industry in which the line must be balanced for multiple types of goods taking into account resource requirements. In order to solve the problem, a hybrid method that combines classical methods for line balancing with an Estimation of Distribution Algorithm is proposed. Computational experiments show that the new procedure improves upon the state of the art when compared using a benchmark set derived from the literature, as well as when compared using data from the manufacturer that originated this research work.
Jordi Pereira. Modelling and solving a cost-oriented resource-constrained multi-model assembly line balancing problem. International Journal of Production Research 2018, 56, 3994 -4016.
AMA StyleJordi Pereira. Modelling and solving a cost-oriented resource-constrained multi-model assembly line balancing problem. International Journal of Production Research. 2018; 56 (11):3994-4016.
Chicago/Turabian StyleJordi Pereira. 2018. "Modelling and solving a cost-oriented resource-constrained multi-model assembly line balancing problem." International Journal of Production Research 56, no. 11: 3994-4016.
Line balancing aims to assign the assembly tasks to the stations that compose the assembly line. A recent body of literature has been devoted to heterogeneity in the assembly process introduced by different workers. In such an environment, task times depend on the worker performing the operation and the problem aims at assigning tasks and workers to stations in order to maximize the throughput of the line. In this work, we consider an interval data version of the assembly line worker assignment and balancing problem (ALWABP) in which it is assumed that lower and upper bounds for the task times are known, and the objective is to find an assignment of tasks and workers to the workstations such that the absolute maximum regret among all of the possible scenarios is minimized. The relationship with other interval data minmax regret (IDMR) problems is investigated, the inapplicability of previous approximation methods is studied, regret evaluation is considered, and exact and heuristic solution methods are proposed and analyzed. The results of the proposed methods are compared in a computational experiment, showing the applicability of the method and the theoretical results to solve the problem under study. Additionally, these results are not only applicable to the problem in hand, but also to a more general class of problems.
Jordi Pereira. The robust (minmax regret) assembly line worker assignment and balancing problem. Computers & Operations Research 2018, 93, 27 -40.
AMA StyleJordi Pereira. The robust (minmax regret) assembly line worker assignment and balancing problem. Computers & Operations Research. 2018; 93 ():27-40.
Chicago/Turabian StyleJordi Pereira. 2018. "The robust (minmax regret) assembly line worker assignment and balancing problem." Computers & Operations Research 93, no. : 27-40.
The objective of territorial design for a distribution company is the definition of geographic areas that group customers. These geographic areas, usually called districts or territories, should comply with operational rules while maximizing potential sales and minimizing incurred costs. Consequently, territorial design can be seen as a clustering problem in which clients are geographically grouped according to certain criteria which usually vary according to specific objectives and requirements (e.g. costs, delivery times, workload, number of clients, etc.). In this work, we provide a novel hybrid approach for territorial design by means of combining a K-means-based approach for clustering construction with an optimization framework. The K-means approach incorporates the novelty of using tour length approximation techniques to satisfy the conditions of a pork and poultry distributor based in the region of Valparaíso in Chile. The resulting method proves to be robust in the experiments performed, and the Valparaíso case study shows significant savings when compared to the original solution used by the company.
Sebastián Moreno; Jordi Pereira; Wilfredo Yushimito. A hybrid K-means and integer programming method for commercial territory design: a case study in meat distribution. Annals of Operations Research 2017, 286, 87 -117.
AMA StyleSebastián Moreno, Jordi Pereira, Wilfredo Yushimito. A hybrid K-means and integer programming method for commercial territory design: a case study in meat distribution. Annals of Operations Research. 2017; 286 (1-2):87-117.
Chicago/Turabian StyleSebastián Moreno; Jordi Pereira; Wilfredo Yushimito. 2017. "A hybrid K-means and integer programming method for commercial territory design: a case study in meat distribution." Annals of Operations Research 286, no. 1-2: 87-117.
Jordi Pereira; Óscar C. Vásquez. The single machine weighted mean squared deviation problem. European Journal of Operational Research 2017, 261, 515 -529.
AMA StyleJordi Pereira, Óscar C. Vásquez. The single machine weighted mean squared deviation problem. European Journal of Operational Research. 2017; 261 (2):515-529.
Chicago/Turabian StyleJordi Pereira; Óscar C. Vásquez. 2017. "The single machine weighted mean squared deviation problem." European Journal of Operational Research 261, no. 2: 515-529.
Eduardo Álvarez-Miranda; Jordi Pereira. Designing and constructing networks under uncertainty in the construction stage: Definition and exact algorithmic approach. Computers & Operations Research 2017, 81, 178 -191.
AMA StyleEduardo Álvarez-Miranda, Jordi Pereira. Designing and constructing networks under uncertainty in the construction stage: Definition and exact algorithmic approach. Computers & Operations Research. 2017; 81 ():178-191.
Chicago/Turabian StyleEduardo Álvarez-Miranda; Jordi Pereira. 2017. "Designing and constructing networks under uncertainty in the construction stage: Definition and exact algorithmic approach." Computers & Operations Research 81, no. : 178-191.
Construct, Merge, Solve & Adapt (CMSA) is a recently proposed hybrid algorithm for combinatorial optimization. At each iteration, the algorithm solves a sub-instance of the original problem instance by means of an exact technique. The incumbent sub-instance is adapted at each iteration, first, by adding solution components present in probabilistically constructed solutions; and, second, by removing solution components that have reached a certain age limit and that do not appear in the optimal solution to the current sub-instance. In this work we propose a refined way for selecting the solution components to be removed from the current sub-instance in those cases in which the exact method employed is an integer linear programming solver. More specifically, the information on the reduced costs of the solution components with respect to the linear programming solution is used for this purpose. Experimental results for the chosen test case, the multidimensional knapsack problem, demonstrate the usefulness of this extension of CMSA.
Christian Blum; Jordi Pereira. Extension of the CMSA Algorithm. Proceedings of the 2016 on SIGMOD'16 PhD Symposium 2016, 285 -292.
AMA StyleChristian Blum, Jordi Pereira. Extension of the CMSA Algorithm. Proceedings of the 2016 on SIGMOD'16 PhD Symposium. 2016; ():285-292.
Chicago/Turabian StyleChristian Blum; Jordi Pereira. 2016. "Extension of the CMSA Algorithm." Proceedings of the 2016 on SIGMOD'16 PhD Symposium , no. : 285-292.
Highlights•The bin packing problem with precedence constraints is investigated.•Its relationship with the assembly line balancing problem is considered.•New dominance rules and lower bounds are developed.•A dynamic programming based heuristic and a branch-and-bound method are proposed.•The results show that the methods outperforms all previous approaches. AbstractThe bin packing problem with precedence constraints (BPP-P) is a recently proposed variation of the classical bin packing problem (BPP), which corresponds to a basic model featuring many underlying characteristics of several scheduling and assembly line balancing problems. The formulation builds upon the BPP by incorporating precedence constraints among items, which force successor items to be packed into later bins than their predecessors.In this paper we propose a dynamic programming based heuristic, and a modified exact enumeration procedure to solve the problem. These methods make use of several new lower bounds and dominance rules tailored for the problem in hand. The results of a computational experiment show the effectiveness of the proposed methods, which are able to close all of the previous open instances from the benchmark instance set within very reduced running times.
Jordi Pereira. Procedures for the bin packing problem with precedence constraints. European Journal of Operational Research 2016, 250, 794 -806.
AMA StyleJordi Pereira. Procedures for the bin packing problem with precedence constraints. European Journal of Operational Research. 2016; 250 (3):794-806.
Chicago/Turabian StyleJordi Pereira. 2016. "Procedures for the bin packing problem with precedence constraints." European Journal of Operational Research 250, no. 3: 794-806.