Peut-on travailler sur les données "approximées" en histoire financière ?

Série Histoire économique quantitative, AFNational audienceDuring the nineteenth century, newspapers publish, day after day, the quotation of the government bond, then in the second half of the century, some stocks ; at each year end, one takes the habit to indicate to the investor the highest quotation and the lowest for each month of the last year. These observations have the great advantage to be easily accessible but present nevertheless some serious disadvantages.Having these series of the highest and the lowest quotation, with doubtful precision, as well as the exact observations, we have questionned the usefulness of a careful data counting. It appeared that this gigantic work, in spite of its rigor, brought us relatively minor corrections and that the conclusions rejoined those previously established. That would lead us to conclude that with a light procedure, one could, without real loss in precision, avoid a particularly heavy work of counting.The demonstration, of empirical order, is undertaken in two steps. The first one makes use of classical econometrics: simple regression, Granger-causality and analysis of the seasonality. The second step uses different techniques, the cointegration and the error correction model.Au XIX e siècle, les journaux publient, jour après jour, le cours des rentes, puis dans la seconde moitié du siècle, de certaines actions ; à la fin de chaque année, on prend l'habitude d'indiquer à l'épargnant le cours le plus haut et le cours le plus bas pour chaque mois de l'année écoulée. Ces observations ont le grand avantage d'être assez facilement accessibles mais présentent toutefois quelques inconvénients sérieux.Disposant de ces séries de cours le plus haut et le plus bas, de précision assez douteuse, ainsi que des observations exactes, nous nous sommes interrogés sur l'utilité d'un dépouillement soigneux des données. Il nous est apparu que ce travail gigantesque n'apportait, en dépit de sa rigueur, que des corrections relativement mineures et que les conclusions rejoignaient celles précédemment établies. Il s'ensuit qu'avec une procédure allégée, on pourrait, sans perte réelle en précision, éviter un travail particulièrement lourd de dépouillement.La démonstration, d'ordre empirique, s'effectue en deux parties. La première utilise l'économétrie classique : la régression simple, la causalité-à-la-Granger et l'analyse de la saisonnalité. La seconde partie utilise d'autres techniques, la cointégration et le modèle à correction d'erreur

Peut-on travailler sur les données "approximées" en histoire financière ?

Au XIX e siècle, les journaux publient, jour après jour, le cours des rentes, puis dans la seconde moitié du siècle, de certaines actions ; à la fin de chaque année, on prend l'habitude d'indiquer à l'épargnant le cours le plus haut et le cours le plus bas pour chaque mois de l'année écoulée. Ces observations ont le grand avantage d'être assez facilement accessibles mais présentent toutefois quelques inconvénients sérieux.Disposant de ces séries de cours le plus haut et le plus bas, de précision assez douteuse, ainsi que des observations exactes, nous nous sommes interrogés sur l'utilité d'un dépouillement soigneux des données. Il nous est apparu que ce travail gigantesque n'apportait, en dépit de sa rigueur, que des corrections relativement mineures et que les conclusions rejoignaient celles précédemment établies. Il s'ensuit qu'avec une procédure allégée, on pourrait, sans perte réelle en précision, éviter un travail particulièrement lourd de dépouillement.La démonstration, d'ordre empirique, s'effectue en deux parties. La première utilise l'économétrie classique : la régression simple, la causalité-à-la-Granger et l'analyse de la saisonnalité. La seconde partie utilise d'autres techniques, la cointégration et le modèle à correction d'erreur.rente 3% ; cours le plus haut ; cours le plus bas ; causalité-Granger ; cointégration ; modèle à correction d'erreur

La théorie du petit monde : un test sur le graphe des administrateurs des compagnies d’assurance en France en 1881

Les réseaux d’administrateurs de sociétés émanant des contacts sociaux qu’ils entretiennent au travers de l’exercice de leur mandat portent à questionnement. L’analyse la structure du graphe des administrateurs des principales compagnies d’assurance en France en 1881 vise à étudier l’existence, dans une perspective historique, d’une structure en réseau dans un secteur de création relativement récente et dont la base d’activité vient de s’élargir. Si tel est le cas, quel type d’architecture do..

Cutting multi-control quantum gates with ZX calculus

Circuit cutting, the decomposition of a quantum circuit into independent partitions, has become a promising avenue towards experiments with larger quantum circuits in the noisy-intermediate scale quantum (NISQ) era. While previous work focused on cutting qubit wires or two-qubit gates, in this work we introduce a method for cutting multi-controlled Z gates. We construct a decomposition and prove the upper bound $\mathcal{O}(6^{2K})$ on the associated sampling overhead, where $K$ is the number of cuts in the circuit. This bound is independent of the number of control qubits but can be further reduced to $\mathcal{O}(4.5^{2K})$ for the special case of CCZ gates. Furthermore, we evaluate our proposal on IBM hardware and experimentally show noise resilience due to the strong reduction of CNOT gates in the cut circuits

Resolution of intramolecular dipoles and push-back effect of individual molecules on a metal surface

Molecules consisting of a donor and an acceptor moiety can exhibit large intrinsic dipole moments. Upon deposition on a metal surface, the dipole may be effectively screened and the charge distribution altered due to hybridization with substrate electronic states. Here, we deposit Ethyl-Diaminodicyanoquinone molecules, which exhibit a large dipole moment in gas phase, on a Au(111) surface. Employing a combination of scanning tunneling microscopy and non-contact atomic force microscopy, we find that a significant dipole moment persists in the flat-lying molecules. Density-functional theory calculations reveal that the dipole moment is even increased on the metal substrate as compared to the gas phase. We also show that the local contact potential across the molecular islands is decreased by several tens of meV with respect to the bare metal. We explain this by the induced charge-density redistribution due to the adsorbed molecules, which confine the substrate's wavefunction at the interface. Our local measurements provide direct evidence of this so-called push-back or cushion effect at the scale of individual molecules.Comment: This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Journal of Physical Chemistry

Variations of vibronic states in densely-packed structures of molecules with intramolecular dipoles

Electrostatic potentials strongly affect molecular energy levels and charge states, providing the fascinating opportunity of molecular gating. Their influence on molecular vibrations remains less explored. Here, we investigate Ethyl-Diaminodicyanoquinone molecules on a monolayer of MoS$_2$ on Au(111) using scanning tunneling and atomic force microscopy and spectroscopy. These molecules exhibit a large dipole moment in gas phase, which we find to (partially) persist on the MoS$_2$ monolayer. The self-assembled structures consist of chains, where the dipoles of neighboring molecules are aligned anti-parallel. Thanks to the decoupling efficiency of the molecular states from the metal by the MoS$_2$ interlayer, we resolve vibronic states of the molecules, which vary in intensity depending on the molecular surrounding. We suggest that the vibrations are strongly damped by electrostatic interactions with the environment

Quantum cohomology via vicious and osculating walkers

We relate the counting of rational curves intersecting Schubert varieties of the Grassmannian to the counting of certain non-intersecting lattice paths on the cylinder, so-called vicious and osculating walkers. These lattice paths form exactly solvable statistical mechanics models and are obtained from solutions to the Yang–Baxter equation. The eigenvectors of the transfer matrices of these models yield the idempotents of the Verlinde algebra of the gauged u^(n)k -WZNW model. The latter is known to be closely related to the small quantum cohomology ring of the Grassmannian. We establish further that the partition functions of the vicious and osculating walker model are given in terms of Postnikov’s toric Schur functions and can be interpreted as generating functions for Gromov–Witten invariants. We reveal an underlying quantum group structure in terms of Yang–Baxter algebras and use it to give a generating formula for toric Schur functions in terms of divided difference operators which appear in known representations of the nil-Hecke algebra

The sl(n)-WZNW Fusion Ring: a combinatorial construction and a realisation as quotient of quantum cohomology

A simple, combinatorial construction of the sl(n)-WZNW fusion ring, also known as Verlinde algebra, is given. As a byproduct of the construction one obtains an isomorphism between the fusion ring and a particular quotient of the small quantum cohomology ring of the Grassmannian Gr(k,k+n). We explain how our approach naturally fits into known combinatorial descriptions of the quantum cohomology ring, by establishing what one could call a `Boson-Fermion-correspondence' between the two rings. We also present new recursion formulae for the structure constants of both rings, the fusion coefficients and the Gromov-Witten invariants.Comment: 61 pages, 2 eps figures; revised version accepted for publication in Advances in Mathematics: some minor typos removed, rewording of the proof to Corollary 6.9 and figure in Example 8.3 change

Innovations en matière de micro finance

DR LEO 2023-10DR LEO - Working paper - 2023-1