Institution
HEC Montréal
Education•Montreal, Quebec, Canada•
About: HEC Montréal is a education organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Vehicle routing problem & Corporate governance. The organization has 1221 authors who have published 5708 publications receiving 196862 citations. The organization is also known as: Ecole des Hautes Etudes Commerciales de Montreal & HEC Montreal.
Topics: Vehicle routing problem, Corporate governance, Heuristic (computer science), Context (language use), Monetary policy
Papers published on a yearly basis
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01 Mar 2003
TL;DR: In this paper, the authors study the use of dual-optimal inequalities to accelerate and stabilize the whole convergence process of column generation and propose two methods for recovering primal feasibility and optimality, depending on the type of inequalities that are used.
Abstract: Column generation is one of the most successful approaches for solving large-scale linear programming problems. However, degeneracy difficulties and long-tail effects are known to occur as problems become larger. In recent years, several stabilization techniques of the dual variables have proven to be effective. We study the use of two types of dual-optimal inequalities to accelerate and stabilize the whole convergence process. Added to the dual formulation, these constraints are satisfied by all or a subset of the dual-optimal solutions. Therefore, the optimal objective function value of the augmented dual problem is identical to the original one. Adding constraints to the dual problem leads to adding columns to the primal problem, and feasibility of the solution may be lost. We propose two methods for recovering primal feasibility and optimality, depending on the type of inequalities that are used. Our computational experiments on the binary and the classical cutting-stock problems, and more specifically on the so-called triplet instances, show that the use of relevant dual information has a tremendous effect on the reduction of the number of column generation iterations.
87 citations
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TL;DR: This paper introduces a mathematical function, called image function, which allows the calculation of the value of the logical parameter associated with a logical variable depending on the state of the system, and shows how all steady states can be derived as solutions to a system of steady-state equations.
87 citations
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TL;DR: This paper introduces models and algorithms for a static dial-a-ride problem arising in the transportation of patients by non-profit organizations such as the Austrian Red Cross, characterized by the presence of heterogeneous vehicles and patients.
Abstract: This paper introduces models and algorithms for a static dial-a-ride problem arising in the transportation of patients by non-profit organizations such as the Austrian Red Cross. This problem is characterized by the presence of heterogeneous vehicles and patients. In our problem, two types of vehicles are used, each providing a different capacity for four different modes of transportation. Patients may request to be transported either seated, on a stretcher or in a wheelchair. In addition, some may require accompanying persons. The problem is to construct a minimum-cost routing plan satisfying service-related criteria, expressed in terms of time windows, as well as driver-related constraints expressed in terms of maximum route duration limits and mandatory lunch breaks. We introduce both a three-index and a set-partitioning formulation of the problem. The linear programming relaxation of the latter is solved by a column generation algorithm. We also propose a variable neighborhood search heuristic. Finally, we integrate the heuristic and the column generation approach into a collaborative framework. The column generation algorithm and the collaborative framework provide tight lower bounds on the optimal solution values for small-to-medium-sized instances. The variable neighborhood search algorithm yields high-quality solutions for realistic test instances.
86 citations
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TL;DR: In this paper, the authors measure the probable impacts of three common interventions aimed at combatting seasonal food insecurity, such as increasing agricultural productivity of the secondary food crops such as cassava, other roots and tubers, and maize.
86 citations
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TL;DR: In this article, the authors discuss formal and informal governance mechanisms that emanate from inside and outside the firm and then review, integrate, and extend the contributions to this topic of the six articles and four commentaries in this special issue.
Abstract: Governance, along with goals and resources, is a key determinant of the distinctiveness and heterogeneity of family firms. Our introduction discusses formal and informal governance mechanisms that emanate from inside and outside the firm and then reviews, integrates, and extends the contributions to this topic of the six articles and four commentaries in this special issue. Building and reflecting on these contributions, we suggest that although formal governance mechanisms inside family firms have unique characteristics, informal governance mechanisms may be equally important, and external mechanisms, both formal and informal, can also profoundly influence the behavior and performance of family firms.
86 citations
Authors
Showing all 1262 results
Name | H-index | Papers | Citations |
---|---|---|---|
Danny Miller | 133 | 512 | 71238 |
Gilbert Laporte | 128 | 730 | 62608 |
Michael Pollak | 114 | 663 | 57793 |
Yong Yu | 78 | 523 | 26956 |
Pierre Hansen | 78 | 575 | 32505 |
Jean-François Cordeau | 71 | 208 | 19310 |
Robert A. Jarrow | 65 | 356 | 24295 |
Jacques Desrosiers | 63 | 173 | 15926 |
François Soumis | 61 | 290 | 14272 |
Nenad Mladenović | 54 | 320 | 19182 |
Massimo Caccia | 52 | 389 | 16007 |
Guy Desaulniers | 51 | 242 | 8836 |
Ann Langley | 50 | 161 | 15675 |
Jean-Charles Chebat | 48 | 161 | 9062 |
Georges Dionne | 48 | 421 | 7838 |