Showing papers by "HEC Montréal published in 2016"
Posted Content•
TL;DR: A neural network-based generative architecture, with latent stochastic variables that span a variable number of time steps, that improves upon recently proposed models and that the latent variables facilitate the generation of long outputs and maintain the context.
Abstract: Sequential data often possesses a hierarchical structure with complex dependencies between subsequences, such as found between the utterances in a dialogue. In an effort to model this kind of generative process, we propose a neural network-based generative architecture, with latent stochastic variables that span a variable number of time steps. We apply the proposed model to the task of dialogue response generation and compare it with recent neural network architectures. We evaluate the model performance through automatic evaluation metrics and by carrying out a human evaluation. The experiments demonstrate that our model improves upon recently proposed models and that the latent variables facilitate the generation of long outputs and maintain the context.
853 citations
TL;DR: In this article, the authors explore three alternative environmental concepts used in transdisciplinary research, and outline some of the epistemological and practical problems that each one poses, paying particular attention to the increasingly popular concept of "circular economy" and contrasts it with the more commonly-used concepts of "environmental sciences" and "sustainable development".
Abstract: The intermeshing of disciplines from the natural sciences, social sciences, engineering and management has become essential to addressing today's environmental challenges. Yet, this can be a daunting task because experts from different disciplines may conceptualize the problems in very different ways and use vocabularies that may not be well understood by one another. This paper explores three alternative environmental concepts used in transdisciplinary research, and outlines some of the epistemological and practical problems that each one poses. It pays particular attention to the increasingly popular concept of “circular economy”, and contrasts it with the more commonly-used concepts of “environmental sciences” and “sustainable development”. In clarifying the nature, meaning and inter-relationship of these alternative concepts, the paper helps trans-disciplinary researchers to understand the opportunities and challenges associated with each one.
693 citations
Proceedings Article•
19 May 2016TL;DR: The authors proposed a neural network-based generative architecture with stochastic latent variables that span a variable number of time steps to generate meaningful, long and diverse responses and maintain dialogue state.
Abstract: Sequential data often possesses hierarchical structures with complex dependencies between sub-sequences, such as found between the utterances in a dialogue. To model these dependencies in a generative framework, we propose a neural network-based generative architecture, with stochastic latent variables that span a variable number of time steps. We apply the proposed model to the task of dialogue response generation and compare it with other recent neural-network architectures. We evaluate the model performance through a human evaluation study. The experiments demonstrate that our model improves upon recently proposed models and that the latent variables facilitate both the generation of meaningful, long and diverse responses and maintaining dialogue state.
619 citations
07 Sep 2016
TL;DR: A co-factorization model, CoFactor, which jointly decomposes the user-item interaction matrix and the item-item co-occurrence matrix with shared item latent factors and provides qualitative results that explain how CoFactor improves the quality of the inferred factors.
Abstract: Matrix factorization (MF) models and their extensions are standard in modern recommender systems. MF models decompose the observed user-item interaction matrix into user and item latent factors. In this paper, we propose a co-factorization model, CoFactor, which jointly decomposes the user-item interaction matrix and the item-item co-occurrence matrix with shared item latent factors. For each pair of items, the co-occurrence matrix encodes the number of users that have consumed both items. CoFactor is inspired by the recent success of word embedding models (e.g., word2vec) which can be interpreted as factorizing the word co-occurrence matrix. We show that this model significantly improves the performance over MF models on several datasets with little additional computational overhead. We provide qualitative results that explain how CoFactor improves the quality of the inferred factors and characterize the circumstances where it provides the most significant improvements.
254 citations
TL;DR: The aims of this survey paper are to provide transportation researchers an overview of the technological and marketing background needed to conduct research in this area, to present a survey of the existing research in the field, and to offer perspectives for future research.
Abstract: Since the mid-2000s, electric vehicles have gained popularity in several countries even though their market share is still relatively low. However, most gains have been made in the area of passenger vehicles and most technical and scientific studies have been devoted to this case. By contrast, the potential of electric vehicular technology for goods distribution has received less attention. The issues related to the use of electric vehicles for goods distribution reveal a wide range of relevant research problems. The aims of this survey paper are to provide transportation researchers an overview of the technological and marketing background needed to conduct research in this area, to present a survey of the existing research in this field, and to offer perspectives for future research.
250 citations
TL;DR: The aim of this survey paper is to classify and review the literature on heterogeneous vehicle routing problems, and presents a comparative analysis of the metaheuristic algorithms that have been proposed for these problems.
214 citations
TL;DR: In this paper, the authors developed a method to quantify the economic value of large-scale renewable energy and found that 20 percent solar would be welfare neutral, with solar installation costs of $1.52 per watt and carbon dioxide social costs of 39.00 per ton, not accounting for offset carbon dioxide.
Abstract: A key problem with solar energy is intermittency: solar generators produce only when the sun is shining, adding to social costs and requiring electricity system operators to reoptimize key decisions. We develop a method to quantify the economic value of large-scale renewable energy. We estimate the model for southeastern Arizona. Not accounting for offset carbon dioxide, we find social costs of $138.40 per megawatt hour for 20 percent solar generation, of which unforecastable intermittency accounts for $6.10 and intermittency overall for $46.00. With solar installation costs of $1.52 per watt and carbon dioxide social costs of $39.00 per ton, 20 percent solar would be welfare neutral.
210 citations
01 Feb 2016
TL;DR: A simulated annealing heuristic based exact solution approach to solve the green vehicle routing problem (G-VRP) which extends the classical vehicle routing problems by considering a limited driving range of vehicles in conjunction with limited refueling infrastructure.
Abstract: We develop a solution approach to solve the green vehicle routing problem.We propose a simulated annealing heuristic to improve the quality of solutions.We present a new formulation having fewer variable and constraints.We evaluate the algorithm in terms of the several performance criterions.Our algorithm is able to optimally solve 22 of 40 benchmark instances. This paper develops a simulated annealing heuristic based exact solution approach to solve the green vehicle routing problem (G-VRP) which extends the classical vehicle routing problem by considering a limited driving range of vehicles in conjunction with limited refueling infrastructure. The problem particularly arises for companies and agencies that employ a fleet of alternative energy powered vehicles on transportation systems for urban areas or for goods distribution. Exact algorithm is based on the branch-and-cut algorithm which combines several valid inequalities derived from the literature to improve lower bounds and introduces a heuristic algorithm based on simulated annealing to obtain upper bounds. Solution approach is evaluated in terms of the number of test instances solved to optimality, bound quality and computation time to reach the best solution of the various test problems. Computational results show that 22 of 40 instances with 20 customers can be solved optimally within reasonable computation time.
168 citations
TL;DR: This work considers a dynamic closed-loop supply chain made up of one manufacturer and one retailer, with both players investing in a product recovery program to increase the rate of return of previously purchased products.
142 citations
TL;DR: In this paper, the macroeconomic effects of deregulating the goods and labor markets were studied and it was shown that deregulation can have short-run recessionary effects, despite being expansionary in the long run.
133 citations
TL;DR: In this paper, the authors investigated the combined impact of depot location, fleet composition and routing decisions on vehicle emissions in city logistics in a city in which goods need to be delivered from a depot to customers located in nested zones characterized by different speed limits.
Abstract: This paper investigates the combined impact of depot location, fleet composition and routing decisions on vehicle emissions in city logistics. We consider a city in which goods need to be delivered from a depot to customers located in nested zones characterized by different speed limits. The objective is to minimize the total depot, vehicle and routing cost, where the latter can be defined with respect to the cost of fuel consumption and CO 2 emissions. A new powerful adaptive large neighborhood search metaheuristic is developed and successfully applied to a large pool of new benchmark instances. Extensive analyses are performed to empirically assess the effect of various problem parameters, such as depot cost and location, customer distribution and heterogeneous vehicles on key performance indicators, including fuel consumption, emissions and operational costs. Several managerial insights are presented.
TL;DR: In this paper, the authors draw on the perspective of marketing as exchange to provide a holistic exploration of food waste in retail and wholesale stores while taking into account the interconnectedness of the entire food supply chain.
Abstract: Food waste is a major problem in industrialized nations, and thus a better understanding of this phenomenon and its inherent complexity is imperative. As gatekeeper to the food supply chain, the retail and wholesale sector is a crucial actor in the pursuit of minimizing food waste. The authors draw on the perspective of marketing as exchange to provide a holistic exploration of food waste in retail and wholesale stores while taking into account the interconnectedness of the entire food supply chain. Through 32 semistructured interviews with store managers, the authors shed light on the issues of food waste and its human reality. The findings reveal the questionable ethics of discarding food; the societal, regulatory, and systemic constraints leading to the occurrence of food waste in stores; and the resulting moral burden on store managers. Building on these factors, the authors outline public policy recommendations in the areas of education and law and provide managerial recommendations for the b...
TL;DR: In this article, the authors investigate the dynamics of cross-listing and corporate social responsibility (CSR) and find that cross-listed firms have better CSR performance than non-cross-listed domestic firms.
Abstract: This paper investigates the dynamics of cross-listing and corporate social responsibility (CSR). Using a sample of 10,815 firm-year observations from 54 countries over the period 2002–2011, we find that cross-listed firms have better CSR performance than non–cross-listed domestic firms. This result is robust to endogeneity and different types of cross-listing. We also find that CSR increases (decreases) significantly after cross-listing in (delisting from) U.S. markets. The positive impact of cross-listing on CSR performance is stronger for firms from countries with weaker institutions, lower country-level sustainability, and higher liability of foreignness, and for firms operating in industries with high litigation risk. Finally, we find that cross-listed firms with better CSR performance exhibit higher valuations.
TL;DR: In this paper, the present state of research on established SME's international involvement is reviewed based on a literature review of 121 articles and an integrative framework is developed to examine the antecedents, outcomes and moderators of SME international involvement.
TL;DR: In this article, the authors rely on set-theoretic methods and a large international dataset of 1,060 multinational companies to explore theoretically and empirically some of the complementarities, costs and contingencies likely to arise in stakeholder management.
Abstract: Instrumental stakeholder theory has largely emphasized the positive effects of investing in stakeholder cooperative relationships in an additive, linear fashion in the sense that the more investments the better. Yet investing in stakeholders can be very costly and the effects of these investments in firm performance are subject to complex internal complementarities and external contingencies. In this article we rely on set-theoretic methods and a large international dataset of 1,060 multinational companies to explore theoretically and empirically some of the complementarities, costs and contingencies likely to arise in stakeholder management.
TL;DR: The authors examined how professions responded to a potential change in jurisdictional boundaries by analyzing the written submissions of five professional associations in reaction to a government proposal to strengthen interprofessional collaboration, relating these responses to the professions' field positions.
Abstract: We examine how professions responded to a potential change in jurisdictional boundaries by analyzing the written submissions of five professional associations in reaction to a government proposal to strengthen interprofessional collaboration, relating these responses to the professions’ field positions. We identify four foci for framing used by the professions to discursively develop their boundary claims: (1) framing the issue of interprofessional collaboration (issue framing), (2) framing of justifications for favored solutions (justifying), (3) framing the profession’s own identity (self-casting), and (4) framing other professions’ identities (altercasting). We find that professions employed these foci differently depending on two dimensions of their field positions – status and centrality. Our study contributes to the literature by identifying distinctive ways through which the foci for framing may be mobilized in situations of boundary contestation, and by theorizing how field position in terms of status and centrality influences actors’ framing strategies.
TL;DR: In this paper, the authors apply the notion of institutional work to understand how managers responsible for newly formed healthcare organizations defined and carried out their individual missions while simultaneously clarifying and operationalizing the government's reform mandate.
Abstract: This article draws on recent developments in institutional theory to better understand the managerial efforts implicated in the implementation of government-led reforms in public sector services. Based on a longitudinal study of a massive reform effort aimed at transforming the province of Quebec’s publicly-funded healthcare system, the article applies the notion of institutional work to understand how managers responsible for newly formed healthcare organizations defined and carried out their individual missions while simultaneously clarifying and operationalizing the government’s reform mandate. We identify and describe the properties of four types of work implicated in this process and suggest that structural work, conceptual work, and operational work need to be underpinned by relational work to offer chances for successful policy reform. By showing the specific processes whereby top-down reform initiatives are taken up by managers and hybridized with existing institutionalized forms and practices, this article helps us better understand both the importance of managerial agency in enacting reform, and the dynamics that lead to policy slippage in complex reform contexts.
TL;DR: This chapter presents an overview of some of the recent developments in the green vehicle routing area, including the description of some vehicle emission models and their applications in road freight transportation.
Abstract: Green vehicle routing is a branch of green logistics which refers to vehicle routing problems where externalities of using vehicles, such as carbon dioxide-equivalents emissions, are explicitly taken into account so that they are reduced through better planning. This chapter presents an overview of some of the recent developments in the area, including the description of some vehicle emission models and their applications in road freight transportation.
TL;DR: In this paper, the authors argue that a systematic approach accompanied by transparent reporting is essential for positivist as well as interpretivist reviews, regardless of their specific type, scope and methods.
Abstract: Recently there has been a great deal of advice published for information systems researchers aiming to conduct standalone literature reviews, and this advice has been, at times, confusing, contradictory and contested. In this opinion paper, we harmonize and resolve some crucial elements of this debate. In our view, literature review articles need to adhere to the same high standards of quality and trustworthiness as other empirical studies. We argue that a systematic approach, accompanied by transparent reporting, is essential for positivist as well as interpretivist reviews, regardless of their specific type, scope and methods. In terms of structure, we first recap the main genres of review articles used by information systems scholars, and present a high-level framework of the steps required to develop a literature review article. For each step, we then explain how the twin concepts of systematicity and transparency should be understood and embedded in the process of developing review papers across a wide range of genres, including positivist aggregative reviews as well as interpretive syntheses using iterative, inductive and abductive approaches.
TL;DR: The HESA successfully combines several metaheuristics and offers a number of new advanced efficient procedures tailored to handle heterogeneous fleet dimensioning and location decisions and a powerful hybrid evolutionary search algorithm (HESA) to solve the FSMLRPTW problem.
TL;DR: In this article, the authors use a new panel dataset to study the network of formal firm linkages within and across 52 aerospace clusters in North America and Europe, and find empirical evidence in support of this proposition.
Abstract: We use a new panel dataset to study the network of formal firm linkages within and across 52 aerospace clusters in North America and Europe. Our theoretical framework, built upon the knowledge-based cluster and global value chains literature, suggests that a reduction in spatial transaction costs has induced clusters to specialize in increasingly fine-grained value chain stages. This should cause the overall network to evolve from a geographically localized structure to a trans-local hierarchical structure that is stratified along value chain stages. Applying community structure detection techniques and organizing sub-networks by linkage type, we find empirical evidence in support of this proposition.
TL;DR: A review of empirical literature on risk aversion (and risk behavior) with a particular focus on insurance demand or consumption is presented in this article, where empirical studies on the demand for insurance considering the use of variables associated with risk aversion.
Abstract: Determinants of risk attitudes of individuals are of great interest in the growing area of behavioral economics that focuses on the individual attributes, psy- chological or otherwise/ that shape common financiai and investment practices. The purpose of this paper is to review the empirical literature on risk aversion (and risk behavior) with a particular focus on insurance demand or consumption. Empirical research on risk aversion may be categorized into two main areas: (1) the measurement and magnitude of risk aversion, and (2) the empirical analysis of sodo-dcmographic variables associated with risk aversion. The paper reviews this literature as well as empirical studies on the demand for insurance considering the use of variables
01 Feb 2016
TL;DR: Two enhancements for the exact solution of the VRPTW by branch-price-and-cut BPC are introduced and a sharper form of the limited-memory subset-row inequalities is developed by representing the memory as an arc subset rather than a node subset.
Abstract: The vehicle routing problem with time windows VRPTW consists of finding least-cost vehicle routes to satisfy the demands of customers that can be visited within specific time windows. We introduce two enhancements for the exact solution of the VRPTW by branch-price-and-cut BPC. First, we develop a sharper form of the limited-memory subset-row inequalities by representing the memory as an arc subset rather than a node subset. Second, from the elementary inequalities introduced by Balas in 1977, we derive a family of inequalities that dominate them. These enhancements are embedded into an exact BPC algorithm that includes state-of-the-art features such as bidirectional labeling, decremental state-space relaxation, completion bounds, variable fixing, and route enumeration. Computational results show that these enhancements are particularly effective for the most difficult instances and that our BPC algorithm can solve all 56 Solomon instances with 100 customers and 51 of 60 Gehring and Homberger instances with 200 customers.
The online appendix is available at https://doi.org/10.1287/ijoc.2016.0744 .
TL;DR: In this paper, the authors investigated the link between the concepts of shopping values and shopping well-being and found that hedonic value, but not utilitarian value, positively influences shopping wellbeing.
TL;DR: A hybrid two-phase optimization algorithm which exploits the potentiality of neighborhood search techniques combined with Monte Carlo simulation is developed to solve the joint advance and allocation scheduling problem taking into account the inherent uncertainty of surgery durations.
Abstract: This paper deals with the Operating Room (OR) planning problem at an operational planning level. The problem addressed consists of two interrelated sub-problems usually referred to as “advance scheduling” and “allocation scheduling”. In the first sub-problem, the decisions considered are the assignment of a surgery date and an OR block to a set of patients to be operated on over a given planning horizon. The second aims at determining the sequence of selected patients in each OR and day. We assume that the duration of surgeries are random variables with known probability distributions. For each sub-problem an integer linear stochastic formulation is given. A hybrid two-phase optimization algorithm which exploits the potentiality of neighborhood search techniques combined with Monte Carlo simulation is developed to solve the overall problem. The approach developed searches for a feasible and robust solution designed to balance the trade-off arising between the hospital and patient perspectives, i.e. maximizing the OR utilization and minimizing the number of patient cancellations. The contribution of this paper is twofold. The former, more methodological, is to provide an efficient algorithmic framework to solve the joint advance and allocation scheduling problem taking into account the inherent uncertainty of surgery durations. The latter, more practical, is to provide a tool to develop robust offline OR schedules which consider the trade-off between reducing surgery cancellations and postponements while maximizing the operating theater utilization. To evaluate the efficiency of the proposed algorithmic approach, in terms of quality of solutions and solution time, we provide a computational analysis on a set of instances based on real data.
TL;DR: This paper introduces, model, and solves a rich multiperiod inventory-routing problem with pickups and deliveries motivated by the replenishment of automated teller machines in the Netherlands using a very large-scale mixed-integer linear programming model.
Abstract: The purpose of this paper is to introduce, model, and solve a rich multiperiod inventory-routing problem with pickups and deliveries motivated by the replenishment of automated teller machines in the Netherlands. Commodities can be brought to and from the depot, as well as being exchanged among customers to efficiently manage their inventory shortages and surpluses. A single customer can both provide and receive commodities at different periods, since its demand changes dynamically throughout the planning horizon and can be either positive or negative. In the case study, new technology provides these machines with the additional functionality of receiving deposits and reissuing banknotes to subsequent customers. We first formulate the problem as a very large-scale mixed-integer linear programming model. Given the size and complexity of the problem, we first decompose it into several more manageable subproblems by means of a clustering procedure, and we further simplify the subproblems by fixing some variables. The resulting subproblems are strengthened through the generation of valid inequalities and solved by branch and cut. We assess the performance of the proposed solution methodology through extensive computational experiments using real data. The results show that we are able to obtain good lower and upper bounds for this new and challenging practical problem.
TL;DR: In this article, a systematic literature review was conducted to synthesize and appraise the extant empirical research on the interplay between country-and firm-level governance mechanisms and the effects on firm outcomes.
Abstract: Manuscript Type
Review
Research Question/Issue
Using a systematic literature review approach, we survey 192 cross-national comparative studies published in 23 scholarly journals in the fields of accounting, economics, finance, and management for the period 2003 to 2014. The purpose is to synthesize and appraise the extant empirical research on the interplay between country- and firm-level governance mechanisms and the effects on firm outcomes. Particular focus is placed on studies that examine firm economic performance.
Research Findings/Results
We identify and distinguish between two groups of cross-national governance studies. The first type compares macro, country-level outcomes and the second compares three different firm-level outcomes: economic performance, governance mechanisms, and strategic decisions. We compare the theoretical frameworks used and further analyze the country-level factors and firm-level governance attributes that have been combined to investigate their interplay and the effects on firm outcomes. We find substantial variation in the use and measurement of country-level factors as well as a variety of causal forms used to explain the combined effects of country- and firm-level governance mechanisms. This wide variability precludes comparison, and consequently prevents identifying consistent patterns of influence between country-level governance factors and firm-level governance mechanisms and/or performance. We identify research gaps and provide fruitful directions for future research on this topic.
Theoretical Implications
The cross-national governance research has been guided mainly by an economic perspective focusing on international differences in the effectiveness of specific governance mechanisms. Few comparative studies have integrated an institutional perspective or examined the external forces that drive the diffusion and use of specific governance mechanisms. Such integrative framework would improve the understanding of cross-national differences in the salient dimensions of country-level governance factors and how they mediate the effectiveness of firm-level governance mechanisms.
Practitioner Implications
Our results reveal that firm- and country-level governance mechanisms have been interacted and combined, either to address various agency problems or to compensate for a weak national environment. This calls for regulators and investors to consider national governance factors when assessing firm-level governance practices.
TL;DR: It is demonstrated that inhibitory control at all ages can actually support creativity, and it is argued that the ability to resist the spontaneous activation of design heuristics, to privilege other types of reasoning, might be critical to generate creative ideas at all age.
Abstract: Developmental cognitive neuroscience studies tend to show that the prefrontal brain regions (known to be involved in inhibitory control) are activated during the generation of creative ideas. In the present article, we discuss how a dual-process model of creativity-much like the ones proposed to account for decision making and reasoning-could broaden our understanding of the processes involved in creative ideas generation. When generating creative ideas, children, adolescents, and adults tend to follow "the path of least resistance" and propose solutions that are built on the most common and accessible knowledge within a specific domain, leading to fixation effect. In line with recent theory of typical cognitive development, we argue that the ability to resist the spontaneous activation of design heuristics, to privilege other types of reasoning, might be critical to generate creative ideas at all ages. In the present review, we demonstrate that inhibitory control at all ages can actually support creativity. Indeed, the ability to think of something truly new and original requires first inhibiting spontaneous solutions that come to mind quickly and unconsciously and then exploring new ideas using a generative type of reasoning.
01 Jan 2016
TL;DR: This paper proposed a neural network-based generative architecture with stochastic latent variables that span a variable number of time steps to generate meaningful, long and diverse responses and maintain dialogue state.
Abstract: Sequential data often possesses hierarchical structures with complex dependencies between sub-sequences, such as found between the utterances in a dialogue. To model these dependencies in a generative framework, we propose a neural network-based generative architecture, with stochastic latent variables that span a variable number of time steps. We apply the proposed model to the task of dialogue response generation and compare it with other recent neural-network architectures. We evaluate the model performance through a human evaluation study. The experiments demonstrate that our model improves upon recently proposed models and that the latent variables facilitate both the generation of meaningful, long and diverse responses and maintaining dialogue state.
TL;DR: In this article, the authors analyze how stakeholders from government, civil society, and industry mobilized modes of justification and forms of power with the aim to influence the moral legitimacy of the fracking technology during a controversy surrounding shale gas exploration.
Abstract: How could a de facto moratorium on shale gas exploration emerge in Quebec despite the broad adoption of fracking in North American jurisdictions, support from the provincial government and a favourable power position initially enjoyed by the oil and gas industry? This paper analyses this turn of events by studying how stakeholders from government, civil society, and industry mobilized modes of justification and forms of power with the aim to influence the moral legitimacy of the fracking technology during a controversy surrounding shale gas exploration. Combining Boltanski and Thevenot's economies of worth theory with Lukes’ concept of power, we analytically induced the justification of power mechanisms whereby uses of power become justified or ‘escape’ justification, and the power of justification mechanisms by which justifications alter subsequent power dynamics. We finally explain how these mechanisms contribute to explaining the controversy's ultimate outcome, and advance current debates on political corporate social responsibility.