French Engineers and the Machinery of Society: X-Crise and the Development of the first Macroeconomic Models in the Nineteen Thirties

The purpose of this article is to highlight the originality of X-Crise, an Ecole Polytechnique association formed in nineteen thirties' France. Firstly il analyses the factors leading the French engineers to look collectively, for the first time of their history, at the big politicoeconomic problems of their epoch. Two factors seem particularly relevant on this matter : their epistemology and value system on one hand, and their perception of the theoretical and political impotence at that time on the other hand.Secondly this paper presents the main original theoretical elements that arose from the group's deliberations. Among them, it exposes the Guillaume brothers' macroeconomic model [1932], one of the very first macroeconomic model produced in France, and Potron's first application to economics of Perron-Frobenius's theorem (Potron [1911] and [1935]).French Engineers - Macroeconomic models - Pragmatism - Mechanics - Perron-Frobenius's theorem

Approches légères pour le raisonnement sur les connaissances et les croyances

Dans cette thèse nous étudions un cadre simple dans lequel modéliser les croyances et les connaissances ainsi que leur évolution dans des systèmes multi-agents. La logique standard de représentation des connaissances est très expressive, mais au prix d'une haute complexité calculatoire. Nous proposons ici un cadre qui permet de capturer plus de situations que d'autres approches existantes tout en restant efficace. En particulier, nous considérons l'application de notre logique à la planification épistémique : étant données une situation initiale et des actions possibles, peut-on atteindre un but fixé ? Cela peut signifier savoir à qui poser des questions pour apprendre des informations, faire en sorte de ne pas être remarquée lorsque l'on lit le courrier de quelqu'un d'autre, ou empêcher quelqu'un d'entendre nos secrets. Nous considérons aussi de possibles extensions à des logiques de croyance, ainsi que les liens entre notre système et d'autres cadres proches.In this thesis we study a lightweight framework in which to model knowledge and beliefs and the evolution thereof in multiagent systems. The standard logic used for this is very expressive, but this comes at a high cost in terms of computational efficiency. We here propose a framework which captures more than other existing approaches while remaining cost-effective. In particular, we show its applicability to epistemic planning: given an initial situation and some possible actions, can we find a way to reach our desired goal? This might mean knowing who to ask in order to learn something, making sure we aren't seen when reading someone else's mail, or preventing someone from overhearing our secrets. We also discuss possible extensions to logics of belief, and the relations between our framework and other related approaches

Reconstructing nonparametric productivity networks

Network models provide a general representation of inter-connected system dynamics. This ability to connect systems has led to a proliferation of network models for economic productivity analysis, primarily estimated non-parametrically using Data Envelopment Analysis (DEA). While network DEA models can be used to measure system performance, they lack a statistical framework for inference, due in part to the complex structure of network processes. We fill this gap by developing a general framework to infer the network structure in a Bayesian sense, in order to better understand the underlying relationships driving system performance. Our approach draws on recent advances in information science, machine learning and statistical inference from the physics of complex systems to estimate unobserved network linkages. To illustrate, we apply our framework to analyze the production of knowledge, via own and cross-disciplinary research, for a world-country panel of bibliometric data. We find significant interactions between related disciplinary research output, both in terms of quantity and quality. In the context of research productivity, our results on cross-disciplinary linkages could be used to better target research funding across disciplines and institutions. More generally, our framework for inferring the underlying network production technology could be applied to both public and private settings which entail spillovers, including intra-and inter-firm managerial decisions and public agency coordination. This framework also provides a systematic approach to model selection when the underlying network structure is unknown

Is the metric signature really electromagnetic in origin?

The program of “pre-metric electromagnetism,” developed by Hehl and collaborators, seeks to derive certain aspects of the spacetime geometry of the world (in particular, metrical signature) from elementary, empirically informed axioms regarding electromagnetic fields. The program should, therefore, be of profound interest to both empiricist and relationalist philosophers. Up to this point, however, pre-metric electromagnetism has received very little attention within the philosophy of physics; this paper seeks to rectify the situation, by engaging in a detailed foundational study of the program. In particular, in this article, we (a) present a streamlined version of the program, identifying key input assumptions, (b) consider the connections between this program and other notable projects in the foundations of spacetime theories, for example, (i) the dynamical approach to spacetime and (ii) constructive axiomatics, and (c) consider in detail the extent to which this program can be generalized beyond electromagnetism. In achieving these tasks, we hope to open up to philosophers an extraordinarily fecund—but lamentably little-known!—project within the foundations of physics

French Engineers and the Machinery of Society: X-Crise and the Development of the first Macroeconomic Models in the Nineteen Thirties

The purpose of this article is to highlight the originality of X-Crise, an Ecole Polytechnique association formed in nineteen thirties' France. Firstly il analyses the factors leading the French engineers to look collectively, for the first time of their history, at the big politicoeconomic problems of their epoch. Two factors seem particularly relevant on this matter : their epistemology and value system on one hand, and their perception of the theoretical and political impotence at that time on the other hand.Secondly this paper presents the main original theoretical elements that arose from the group's deliberations. Among them, it exposes the Guillaume brothers' macroeconomic model [1932], one of the very first macroeconomic model produced in France, and Potron's first application to economics of Perron-Frobenius's theorem (Potron [1911] and [1935])

Discrete space-time geometry and skeleton conception of particle dynamics

It is shown that properties of a discrete space-time geometry distinguish from properties of the Riemannian space-time geometry. The discrete geometry is a physical geometry, which is described completely by the world function. The discrete geometry is nonaxiomatizable and multivariant. The equivalence relation is intransitive in the discrete geometry. The particles are described by world chains (broken lines with finite length of links), because in the discrete space-time geometry there are no infinitesimal lengths. Motion of particles is stochastic, and statistical description of them leads to the Schr\"{o}dinger equation, if the elementary length of the discrete geometry depends on the quantum constant in a proper way.Comment: 22 pages, 0 figure