Search results for " representation"
showing 10 items of 811 documents
Séparation des orbites coadjointes d'un groupe exponentiel par leur enveloppe convexe
2008
Resume Revenant sur la question de la separation des representations unitaires irreductibles d'un groupe de Lie exponentiel G par leur application moment, nous presentons ici une nouvelle solution : au lieu de prolonger l'application moment a l'algebre enveloppante de G , nous proposons de definir une application (non lineaire) Φ de g ∗ dans le dual g + ∗ de l'algebre de Lie d'un groupe resoluble G + , de prolonger les representations de G a G + de telle facon que les orbites coadjointes correspondantes de G + soient caracterisees par l'adherence de leur enveloppe convexe. Ceci nous permet de separer les representations irreductibles de G .
Norms of harmonic projection operators on compact Lie groups
1988
In order to simplify the notation, we will assume throughout that G is connected, simply connected and semisimple. Sharp estimates for vp(z 0 when G = SU(2) have been obtained by Sogge [6], who proved that Vp(Zt) ~ d~ tl/v), where y(t) is the function which is affine on [1/2, 3/4] and on [3/4, 1] and is such that 7(1/2)=0, 7(3/4)=1/4, 7(1)=1. Two results in the literature give crucial estimates from below for vp(n) in the general case. The first estimate concernes the LP'-norm of the character X, : if ,~, is the highest weight of n and 0 is half the sum of the positive roots, then II x=llp,--> + 011-dimG/p" (1.2)
How Electoral Institutions Change the Influence of World Trade Integration on Trade Policies
2014
World integration levels influence opportunity costs of maintaining restrictive national trade policies. In an integrated world, restrictive trade policies are more costly than in a context of low overall levels of world market integration. We argue that policy makers can be expected to react to these varying incentives to liberalize the trade regimes of their countries, yet do so not in a uniform fashion across countries. Rather, the responsiveness to changes in levels of world trade integration is conditional upon the electoral system the country in question employs. This is due to the fact that opportunity cost considerations increase in importance with a) the degree to which policy make…
Communication Design for the Dissemination of Scientific Knowledge. Languages, Tools, Technologies, Collaborative Processes for Museum Education
2019
Il testo propone l’analisi di un articolato processo di ricerca-azione, avviato in occasione di alcune sperimentazioni didattico-scientifiche nate dalla collaborazione tra le discipline del design, della rappresentazione multimediale, delle scienze botaniche nell’Università di Palermo. L’esperienza proposta è stata centrata sulla comunicazione scientifica e sull’elaborazione di prodotti comunicativi per la didattica museale e istituzionale dell’Orto Botanico di Palermo. In quest’occasione sono stati sperimentati strumenti progettuali, tecnologie e modalità di espressione successivamente rielaborati anche in un progetto di sviluppo territoriale, che ha portato alla realizzazione del “Micromu…
Encoding numbers: behavioral evidence for processing-specific representations.
2006
The aim of this study was to test the hypothesis of a complex encoding of numbers according to which each numerical processing requires a specific representational format for input. In three experiments, adult participants were given two numbers presented successively on screen through a self-presentation procedure after being asked to add, to subtract, or to compare them. We considered the self-presentation time of the first number as reflecting the complexity of the encoding for a given planned processing. In line with Dehaene's triple-code model, self-presentation times were longer for additions and subtractions than for comparisons with two-digit numbers but longer for subtractions than…
Down Syndrome and Referential Communication: Understanding and Production
2012
Abstract This study aimed to evaluate the ability of referential communication in subjects with Down Syndrome (DS). We evaluated the possibility that the referential communication is the result of a set of cognitive factors, verbal and nonverbal through the evaluation of relationship between cognitive abilities in individuals with DS and typically developing. In particular, we have identified some critical dimensions of communicative function, such as the referential communication, which means the subject's ability to produce o the listener or messages “referentially oriented”, ie messages that are characterized by “clarity or ambiguity referential”. The referential communication skills, in…
An Innovative Ambient Identification Method
2020
Ambient modal identification, also known as Operational Modal Analysis (OMA), aims to identify the modal properties of a structure based on vibration data collected when the structure is under its operating conditions, i.e., no initial excitation or known artificial excitation. This procedure for testing and/or monitoring historic buildings, is particularly attractive for civil engineers concerned with the safety of complex historic structures. However, since the external force is not recorded, the identification methods have to be more sophisticated and based on stochastic mechanics. In this context, this contribution will introduce an innovative ambient identification method based on appl…
The Role of Sourcing in Discourse Comprehension
2017
This chapter provides a theoretical background by discussing different frameworks relevant for understanding the role of sourcing in discourse comprehension. It reviews empirical work on students' sourcing skills and the role of individual and contextual factors in sourcing and discusses the nature and particular challenges of sourcing in digital contexts and review research on sourcing in such contexts. The chapter analyses intervention work aiming to improve students' consideration and evaluation of source features when dealing with multiple documents and also reviews measures used to assess sourcing skills in the research literature. Developmental psychology research on social cognition …
Low-Rate Reduced Complexity Image Compression using Directionlets
2006
The standard separable two-dimensional (2-D) wavelet transform (WT) has recently achieved a great success in image processing because it provides a sparse representation of smooth images. However, it fails to capture efficiently one-dimensional (1-D) discontinuities, like edges and contours, that are anisotropic and characterized by geometrical regularity along different directions. In our previous work, we proposed a construction of critically sampled perfect reconstruction anisotropic transform with directional vanishing moments (DVM) imposed in the corresponding basis functions, called directionlets. Here, we show that the computational complexity of our transform is comparable to the co…
Complex group algebras of finite groups: Brauer’s Problem 1
2005
Brauer’s Problem 1 asks the following: what are the possible complex group algebras of finite groups? It seems that with the present knowledge of representation theory it is not possible to settle this question. The goal of this paper is to announce a partial solution to this problem. We conjecture that if the complex group algebra of a finite group does not have more than a fixed number m m of isomorphic summands, then its dimension is bounded in terms of m m . We prove that this is true for every finite group if it is true for the symmetric groups.