Portail HAL EHESS (École des hautes études en sciences sociales)
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Inexact subgradient methods for semialgebraic functions
No full textMotivated by the extensive application of approximate gradients in machine learning and optimization, we investigate inexact subgradient methods subject to persistent additive errors. Within a nonconvex semialgebraic framework, assuming boundedness or coercivity, we establish that the method yields iterates that eventually fluctuate near the critical set at a proximity characterized by an distance, where denotes the magnitude of subgradient evaluation errors, and encapsulates geometric characteristics of the underlying problem. Our analysis comprehensively addresses both vanishing and constant step-size regimes. Notably, the latter regime inherently enlarges the fluctuation region, yet this enlargement remains on the order of . In the convex scenario, employing a universal error bound applicable to coercive semialgebraic functions, we derive novel complexity results concerning averaged iterates. Additionally, our study produces auxiliary results of independent interest, including descent-type lemmas for nonsmooth nonconvex functions and an invariance principle governing the behavior of algorithmic sequences under small-step limits
Too risky to hedge: An experiment on narrow bracketing
No full textInternational audienceNarrow bracketers who are myopic in specific decisions would fail to consider preexisting risks in investment and neglect hedging opportunities. Growing evidence has demonstrated the relevance of narrow bracketing. We take a step further in empirical investigation and study individual heterogeneity in narrow bracketing. Specifically, we use a lab experiment in investment and hedging that elicits subjects' preferences on rich occasions to uncover the individual degree of narrow bracketing without imposing distributional assumptions. Combining prospect theory and narrow bracketing can explain our findings: Subjects who invest more also insure more, and subjects insure significantly less in the loss domain than in the gain domain. More importantly, we show that the distribution of the individual degree of narrow bracketing is skewed at two extremes, yet with a substantial share of people in the middle who partially suffer from narrow bracketing. Neglecting this aspect, we would overestimate the severity of narrow bracketing and misinterpret its relation with individual characteristics.</div
中国古典书画美学的法兰西变奏——访法国国家科学研究院汉学家幽兰
No full textInternational audienceFollowing the interview with Professor Yolaine Escande September 2022 on the value and function of Chinese painting and calligraphy theories, the difficulties and limitations of overseas translation and research on Chinese painting and calligraphy theories, the mode of translation and publication of translations, and the teaching and dissemination of classical Chinese paintings and calligraphy, the author further discussed with Professor Yolaine Escande during her visit to France in September 2023, and she put forward some insights on the translation and research practice of Chinese culture, providing thoughts and inspirations for promoting the dissemination of Chinese culture abroad and enhancing the mutual appreciation of civilisations.继2022年9月与幽兰教授围绕中国书画理论的价值与功用、海外中国书画理论翻译及研究的难点与局限、译本的翻译及出版模式、中国古典书画的教学与传播等系列问题进行线上访谈后，笔者于2023年9月法国访学期间进一步同幽兰教授展开探讨，幽兰教授结合其翻译及研究实践提出见解，为推动中国文化海外传播、增进文明互通互鉴提供思考与启示
Après la proj... Discussion autour du film « Monikondee », de Lonnie Van Brummelen, Siebren De Haan, Tolin Erwin Alexander
No full textPour la 9e année consécutive, la BULAC est lieu associé du Cinéma du réel, rendez-vous incontournable du film documentaire international. La dimension internationale de la programmation résonne particulièrement à la BULAC, qui fait le choix de mettre à l’honneur des films ancrés dans les aires géolinguistiques que recouvrent ses collections. Les projections sont accompagnées de débats et de pastilles vidéos avec les réalisateurs, des étudiants et des enseignants-chercheurs. Sélection BULAC 2025 : « Fantômes du passé, cinéma d'à présent » Filmer les fantômes qui nous hantent ne les chasse pas... Mais parler d'eux les fait trembler. Au cours de trois soirées de projections-débats, neuf documentaires vous guideront de l’Asie à l’Europe de l’Est, en passant par l’Amérique du Sud et l’Afrique, à la rencontre de celles et ceux dont les vies sont tourmentées par les violences qui jalonnent notre histoire collective. Fantômes d'aujourd'hui (1 rue Angarskaia, Loin de moi la colère), ou qui traversent les générations comme des échos qui se perpétuent (Monikondee, About the Pink Cocoon, First Light, Balane 3), spectres dissimulés imperceptiblement dans l’intimité de nos esprits (Air Base, Inventory, Manal Issa) : autant de témoignages sans concession pour dépeindre l’humain, autant de sujets à débats pour le cinéma et les sciences humaines
Après la proj... Discussion autour du film « 1 rue Angarskaia », de Rostislav Kirpicenko
No full textPour la 9e année consécutive, la BULAC est lieu associé du Cinéma du réel, rendez-vous incontournable du film documentaire international. La dimension internationale de la programmation résonne particulièrement à la BULAC, qui fait le choix de mettre à l’honneur des films ancrés dans les aires géolinguistiques que recouvrent ses collections. Les projections sont accompagnées de débats et de pastilles vidéos avec les réalisateurs, des étudiants et des enseignants-chercheurs. Sélection BULAC 2025 : « Fantômes du passé, cinéma d'à présent » Filmer les fantômes qui nous hantent ne les chasse pas... Mais parler d'eux les fait trembler. Au cours de trois soirées de projections-débats, neuf documentaires vous guideront de l’Asie à l’Europe de l’Est, en passant par l’Amérique du Sud et l’Afrique, à la rencontre de celles et ceux dont les vies sont tourmentées par les violences qui jalonnent notre histoire collective. Fantômes d'aujourd'hui (1 rue Angarskaia, Loin de moi la colère), ou qui traversent les générations comme des échos qui se perpétuent (Monikondee, About the Pink Cocoon, First Light, Balane 3), spectres dissimulés imperceptiblement dans l’intimité de nos esprits (Air Base, Inventory, Manal Issa) : autant de témoignages sans concession pour dépeindre l’humain, autant de sujets à débats pour le cinéma et les sciences humaines
Appraising the central tendency of distributions of a cardinal and an ordinal variable
No full textThis paper provides a simple uni…ed axiomatic framework for appraising the central tendency of distributions of a single attribute (pie) among a collection of individuals depending upon the available measurement of the attribute. Two types of measurement are considered: cardinal and ordinal. For each of them, three properties are posited on an ordering of distributions of numbers among individuals. The two …rst properties are the anonymity requirement that permutations of the same list of numbers be equivalent and the weak Pareto requirement that a strict increase in the value of the variable for all individuals be favorably appraised. The third property requires that inverting the numerical measurement of the variable leads to an inversion of the ranking of the any two distributions to which the inversion is applied. The mean of a distribution is shown to be the only ordering of distributions consistent with cardinal measurability that satis…es those three requirements in the cardinal context while the median is the only such ranking consistent with ordinal measurability of the variable that sat-is…es those same requirement if the number of individuals is odd. If the number of individuals is even, then those three requirements applied to the ordinal context are shown to be inconsistent
Prescribing High-Priced Cancer Drugs: Rethinking Physicians’ Choice Regarding Expensive Treatments
No full textInternational audienceAs the prices of cancer treatments are constantly rising, reaching tens and hundreds of thousands of euros per patient, this article examines the existence and impact of these prices in everyday hospital practice and in relation to medical autonomy. Our study takes place in the French health care system, which is characterized by the coverage of health care costs by the health insurance system. Through ethnographic observations carried out in hematology and thoracic oncology departments, the study explores how prices, although invisible and excluded from medical practice, can come into play in situations of tension at the boundaries of medical, administrative and financial prescriptive frameworks. However, this paper shows how the innovative and complex nature of these costly treatments can be reinterpreted in terms of value and even become a source of credit
(2024) - Premiers pas vers une identification technique des motifs d’impression, in Bignon-Lau O (dir.), Peschaux C (co-dir.), Rapport intermédiaire d’opération archéologique programmée du site de Pincevent (La Grande-Paroisse, Seine-et-Marne) 2024 (Triennale 2023-2025) Site n° 77210 AP
No full textInformality: Issue 2
No full textNational audienceMost low- and middle-income countries are characterised by a large informal sector, which implies that a substantial fraction of economic activity and livelihoods in these countries goes on completely unregulated. This has important implications for the behaviour of firms, workers, families, and consumers, which combine to have important effects on aggregate outcomes such as productivity, output, growth, and overall economic wellbeing. This VoxDevLit summarises a wide range of studies from well-identified empirical analyses to macro and structural equilibrium models of informality. The final goal is to provide an accessible, integrated understanding of the causes and consequences of informality for economic development