Université Panthéon-Assas Paris 2

• Paris, France
Recent publications
In his book The Community of Advantage, Sugden proposes a form of normative economics that is almost free of the concept of preferences. Specifically, Sugden relies on the idea that everyone can accept the principle that more opportunities is better than less. Yet, this approach cannot be easily applied to the choice of economic reforms that fail to provide more opportunities for everyone. This paper complements an approach proposed by Sugden to deal with non-nested opportunity sets. We rely on the idea that people should take responsibility for the choices that were not endorsed before the reform takes place. In this perspective, a reform project is admissible if it allows people to stick to their initial choices and provides them with a rich set of opportunities (that is, the new opportunity regime must also satisfy Sugden’s Strong Interactive Opportunity Criterion). As an illustration, we show how routine redistribution schemes can make free trade be preferred to autarky even if it does not provide more opportunities for everyone.
The literature on blockchain technology in operations and supply chain management falls short in elaborating salient blockchain architectural features. Most often, it attempts to capture the difference between the public, private and consortium blockchain systems. To advance our knowledge of this distributed technology and help in a better understanding of its various applications, we focus on the consensus algorithms deployed within blockchain systems. We introduce the Proof of Work (PoW), Proof of Stake (PoS), Delegated Proof of Stake (DPoS), Proof of Authority (PoA) and Practical Byzantine Fault Tolerance (PBFT). Our paper demonstrates that many blockchain architectures and new supply chain configurations can emerge with the change in the blockchain consensus mechanism. We focus on the healthcare supply chain, one of the most appealing use cases for blockchain, to outline the architecture of state-of-the-art blockchain systems. This research is a step forwards illustrating the significant change in the concepts and practices towards fully decentralised supply chains.
A group of experts, for instance climate scientists, is to advise a decision maker about the choice between two policies f and g. Consider the following decision rule. If all experts agree that the expected utility of f is higher than the expected utility of g, the unanimity rule applies, and f is chosen. Otherwise, the precautionary principle is implemented and the policy yielding the highest minimal expected utility is chosen. This decision rule may lead to time inconsistencies when adding an intermediate period of partial resolution of uncertainty. We show how to coherently reassess the initial set of experts’ beliefs so that precautionary choices become dynamically consistent: new beliefs should be added until one obtains the smallest “rectangular set” that contains the original one. Our analysis offers a novel behavioral characterization of rectangularity and a prescriptive way to aggregate opinions in order to avoid sure regret.
We introduce a novel approach to exploit mixed precision arithmetic for low-rank approximations. Our approach is based on the observation that singular vectors associated with small singular values can be stored in lower precisions while preserving high accuracy overall. We provide an explicit criterion to determine which level of precision is needed for each singular vector. We apply this approach to block low-rank (BLR) matrices, most of whose off-diagonal blocks have low rank. We propose a new BLR LU factorization algorithm that exploits the mixed precision representation of the blocks. We carry out the rounding error analysis of this algorithm and prove that the use of mixed precision arithmetic does not compromise the numerical stability of the BLR LU factorization. Moreover, our analysis determines which level of precision is needed for each floating-point operation (flop), and therefore guides us toward an implementation that is both robust and efficient. We evaluate the potential of this new algorithm on a range of matrices coming from real-life problems in industrial and academic applications. We show that a large fraction of the entries in the LU factors and flops to perform the BLR LU factorization can be safely switched to lower precisions, leading to significant reductions of the storage and expected time costs, of up to a factor three using fp64, fp32, and bfloat16 arithmetics.
We propose a new notion of coalitional equilibria, the strong β\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}-hybrid solution, which is a refinement of the hybrid solution introduced by Zhao. Zhao’s solution is well suited to study situations where people cooperate within coalitions but where coalitions compete with one another. This paper’s solution, as opposed to the hybrid solution, assigns to each coalition a strategy profile that is strongly Pareto optimal. Moreover, like the β\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}-core, deviations by subcoalitions of any existing coalition are deterred by the threat of a unique counter-strategy available to the non-deviating players. Zhao proved the existence of existence of strong β\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta$$\end{document}-hybrid solution for transferable utility games with compact and convex strategy spaces and concave continuous payoff functions. Here, we extend his result to non-transferable utility games.
This study focuses on the effects of user interfaces in mobile commerce (m-commerce) on the perceived ease of use and related consumer behaviors when controlled for environmental conditions (sunshine, humidity, and brightness). Effects were tested in real-time contexts (outdoor m-commerce). Specifically, three key design attributes related to commercial website interfaces were examined using a full factorial plan (222): color contrast, layout, and font type. A website selling music CDs was created for the experiment. Data were collected through an online questionnaire (n=560) to investigate potential direct and interaction effects of these interface attributes. The results show that an m-commerce website with a positive color contrast (light text on a dark background) and airy line spacing with a sans-serif font (Arial) is perceived as easier to use when engaged in outdoor m-commerce. This combination of interface attributes is associated with higher intentions to purchase as well as an increase in revisits and recommendations of the website. The implications for both m-commerce research and practice are discussed.
I provide estimates of compensated elasticities of labor income with respect to the Marginal Net‐of‐Tax Rate on the 2006–2015 period for France, exploiting not only income tax reforms but also means‐tested benefits reforms. I use semiparametric graphical evidence and a classic 2SLS estimation applied to a rich data set including both financial and socio‐demographic variables. I obtain an estimated compensated elasticity on the intensive margin around 0.2‐0.3 in response to income tax reforms, around 0.1 in response to in‐work benefit reforms, while I found no statistically significant response to family allowance reforms. I show that the difference between elasticities contradicts the theoretical prediction of the classical labor supply model. These asymmetric responses are very robust to a large number of robustness checks. The most plausible explanation is that income tax reforms are more salient and better perceived than benefit reforms. I also highlight an average compensated elasticity of 0.1 for all transfers on the intensive margin and provide heterogeneous elasticities depending on types of people, which could be used for optimal tax analyses. This article is protected by copyright. All rights reserved
We provide an axiomatic characterization of recursive MaxMin preferences that stem from a (possibly) incomplete relation representing preference judgements that are justified by objective probabilistic information. To ensure that her choice behavior be informed by objective information, dynamically consistent, and ambiguity averse, the decision-maker evaluates alternatives by their minimal expected value over the rectangular hull of the objective information set. The characterization builds upon two axioms that naturally combine the three requirements in a behavioral way. Our main result suggests a principled justification for the use of recursive MaxMin preferences in applications to dynamic choice problems.
This paper explores the relation between campaign spending and votes, in France, relying on political financing reforms as a quasi-natural experiment to assess if and how spending affects votes, for both incumbent and challenger candidates in multiparty legislative elections. The French reforms were adopted in the mid-1990s, modifying the fundraising rules in three important ways: (1) spending limits were reduced, (2) legal entities no longer were allowed to fund candidates, and (3) the maximal amount of candidates’ personal campaign spending reimbursed by the State was raised. We study observations on two consecutive legislative elections, one before and one after the reforms. The difference in campaign expenses across elections turns out to be strongly affected by the reforms: candidates from the extreme parties (far left and far right) increased their expenditures substantially, while the candidates fielded by moderate parties reduced them considerably. Focusing on politicians running in both elections, we estimate the impact of spending using first-difference panel data methods and TSLS. Our instrumental variables for the difference in spending are constructed from the regulatory reforms. We find that spending by incumbents did not have statistically significant effects on their vote shares. Spending by challengers is statistically significant but the impact nevertheless is economically small.
The analysis of French municipalities’ public personnel expenditures allows us to study the issue of the size of the local public sector. We concentrate on two paths that French authorities have followed to limit it, i.e., the promotion of inter-municipal cooperation (IMC) and the cut in grants received by municipalities. Our objective is to evaluate their respective role in the evolution of public personnel expenditures at the municipal level, in a context where local politics comes into play. We consider a large panel dataset of municipalities embedded in IMC structures between 2011 and 2018. Our main results, obtained using an original identification strategy, are threefold. We first find evidence that a substitution effect between municipal and IMC personnel expenditures is at work. Second, we find a partisan distorsion through the grant allocation: despite its formula-based definition, aligned and unaligned municipalities are treated differently by the central government. Third, we show that cuts in grants lead to cuts in municipalities’ public wage bills, while partisanship hinders such cuts.
Launched in 2019, the French Citizens’ Convention for Climate (CCC) tasked 150 randomly chosen citizens with proposing fair and effective measures to fight climate change. This was to be fulfilled through an “innovative co-construction procedure”, involving some unspecified external input alongside that from the citizens. Did inputs from the steering bodies undermine the citizens’ accountability for the output? Did co-construction help the output resonate with the general public, as is expected from a citizens’ assembly? To answer these questions, we build on our unique experience in observing the CCC proceedings and documenting them with qualitative and quantitative data. We find that the steering bodies’ input, albeit significant, did not impair the citizens’ agency, creativity, and freedom of choice. While succeeding in creating consensus among the citizens who were involved, this co-constructive approach, however, failed to generate significant support among the broader public. These results call for a strengthening of the commitment structure that determines how follow-up on the proposals from a citizens’ assembly should be conducted.
Research extends in all directions regarding the usage of blockchain technology in operations, logistics, and supply chain management. However, little is known about the role of blockchain in mitigating the risk of specific supply chain disruptions. Therefore, this paper investigates which disruptions in the supply chain can be mitigated through blockchain as well as how these issues can be alleviated. By utilising data collected from a systematic literature review, we find that blockchain mitigates disruptions that are related to specific supply and demand risks: behavioural uncertainties, poor information security, fraud and counterfeit risks, data loss and human errors, operational risks, transactional risks, foodborne illness risks, and information asymmetries. Blockchain is useful in these areas because, as a distributed ledger technology, it integrates the supply chain’s communication systems with a unified platform that improves information-sharing and processing capabilities. Our study represents a step towards improved understanding of blockchain’s positive impact in supply chain and information management-related fields.
Given that commercial friendships between luxury salespeople and customers tend to elicit great loyalty from customers, it is relevant and timely to study how luxury salespeople manage these relationships. We build on ethnographic fieldwork in luxury stores, focusing on the interaction between salespeople and habituated luxury customers, to offer an analysis of commercial friendships in these settings. Our findings suggest that luxury foregrounds the importance of secrets and gifts in commercial friendships. Furthermore, the luxury context brings out the darker, more challenging side of commercial friendships. As intimacy develops between salespeople and customers, another kind of relationship emerges in which salespeople are often at the beck and call of their wealthy customers, leading them to fall into the intimacy trap. We propose some pathways to help salespeople manage these critical relationships and to avoid the intimacy trap.
The relationship between the unemployment rate and the evolution of human capital is different depending on whether one subscribes to a neoclassical logic or to a hysteresis theory. This paper proposes that when the unemployment rate reaches a high level for some time, the persistence phenomenon, or hysteresis, weakens the attractive forces of the natural rate of unemployment. The unemployment rate can then reach a different equilibrium value. However, according to Blanchard and Summers, this equilibrium is unstable and fragile. In the second part of this paper, we propose an indicator to measure the intensity of the attraction forces of the natural rate of unemployment. The empirical values of this index show the weak attraction forces of the natural rate of unemployment in economies with high levels of long-term unemployment.
Résumé Près d’un tiers des candidats au don de rein présente une incompatibilité (HLA et/ou ABO) avec le receveur pour lequel il s’engage. Le don croisé permet d’échanger des donneurs potentiels et donne l’accès à une greffe rénale compatible. La loi de bioéthique de 2011 a autorisé le don croisé en France avec une réciprocité entre 2 paires « donneur-receveur » incompatibles. Un faible nombre de greffes a été réalisé du fait d’une autorisation trop limitée en comparaison à d’autres pratiques européennes. Cette étude présente les perspectives de la nouvelle loi de bioéthique, promulguée en 2021, qui élargit les pratiques autorisées pour le don croisé en France. Les deux évolutions simulées sont l’augmentation du nombre de paires engagées dans un échange croisé à 6 (contre 2 paires actuellement) et le recours à un donneur décédé en substitution à l’un des donneurs vivants. Différents scénarii sont simulés à partir des données de l’Agence de la biomédecine ; les paires incompatibles inscrites dans le programme de don croisé en France entre décembre 2013 et février 2018 (78 paires incompatibles), les greffes incompatibles réalisées au cours de la même période (476 paires incompatibles) et les caractéristiques des donneurs décédés ainsi que les propositions faites sur cette période. L’augmentation du nombre de paires a un effet limité sur le nombre de greffes, qui passe de 18 (23 % des receveurs) dans le système actuel à 25 (32 % des receveurs) lorsque 6 paires peuvent être engagées dans un échange croisé. Le recours à un donneur décédé augmente significativement le nombre de greffes, qui passe à 41 (52 % des receveurs). Cette étude permet d’évaluer l’augmentation des possibilités de greffes rénales par don croisé suite à la nouvelle loi de bioéthique. Un groupe de travail et une campagne d’information des professionnels et des patients seront nécessaires pour sa mise en œuvre, dont les résultats seront d’autant plus importants que la participation sera élevée.
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