942 resultados para Hilbert symbol


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Abstract This seminar will introduce an initial year of research exploring participation in the development of a bilingual symbol dictionary. Symbols can be a communication and literacy ‘lifeline’ for those unable to communicate through speech or writing. We will discuss how an online system has been built to overcome language, cultural and literacy skill issues for a country where 86% are expatriates but the target clients are Arabic born individuals with speech and language impairments. The symbols in use at present are inappropriate and yet there is no democratic way of providing a ‘user voice’ for making choices, let alone easy mechanisms for adapting and sharing newly developed symbols across the nation or extended Arabic world. This project aims to change this situation. Having sourced a series of symbols that could be adapted to suit user’s needs, the team needed to encourage those users, their carers and therapists to vote on whether the symbols would be appropriate and work with those already in use. The first prototype was developed and piloted during the WAISfest in 2013. The second phase needs further voting on the most suitably adapted symbols for use when communicating with others. There is a requirement to have mechanisms for evaluating the outcome of the votes, where symbols fail to represent accurate meanings, have inappropriate colours, representations and actions etc. There also remains the need to collect both quantitative and qualitative data. Not easy in a climate of acceptance of the expert view, a culture where to be critical can be a problem and time is not of the essence.

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Dos hecho fundamentales harán que surja la teoría formalista: 1õ. Surge a principios del siglo XIX teorías no euclídeas y 2õ. Teorías de conjuntos y crisis de fundamentos de finales del siglo XIX. Simutalneamente el problema de la fundamentación de la matemática daba lugar a las distintas escuelas que iban a adoptar diferentes tratamientos: la escuela logicista defendida por Bernard Russel; la escuela intuicionista al frente de la que estaba Brouwer; y la escuela formalista encabezada por Hilbert. El programa de la última buscará una demostración consistente para un cálculo formal axiomatizado. Hilbert introduce una sutil diferencia entre la teoría matemática, constituida por todas las fórmulas de la matemática intuitiva y la metamatemática que tiene por objeto el estudio de la misma matemática y que estará formada por todas las proposiciones que se pueden hacer a partir de las fórmulas matemáticas. Así, pues en síntesis en primer lugar una teoría matemática de carácter informal como por ejemplo la aritmétic; después un sistema formal del cual la aritmética sería una interpretación y; en tercer lugar, el estudio del sistema formal y de sus propiedades estructurales que recibe el nombre de metamatemática, en donde el lenguaje y el racionamiento vuelven a tener un carácter informal. La idea básica de Hilbert consiste en estudiar y analizar el sistema formal hasta que se pueda poner de relieve la imposibilidad de una contradicción para la aritmética clásica. En 1931 se puso de manifiesto la imposibilidad de demostrar la consistencia de un sistema formal suficientemente amplio para contener toda la aritmética. Dicha demostración iba a suponer la renuncia del objetivo fundamental del programa de Hilbert. A pesar de la pérdida del objetivo básico de su programa (de Hilbert), el estudio de los sistemas formales proporcionó importantes conocimientos de la lógica formal y abrió nuevas perspectivas de estudio. La aparicición y desarrollo del formalismo, como estilo y método de trabajo para la matemática ha dado sus frutos en el terreno de la fundamentación donde propiamente había nacido y es pertinente situar su principal aportación que es darles métodos para analizar sus estructuras y sus nociones fundamentales con el fin de precisar su claridad, etcétera. El papel social constructivo que la matemática jugó en la edificación del capitalismo comercial e industrial fue esencialmente lo que hizo que se fomentara su estudio, aunque tuviera que adoptar formas cada vez más abstractas para llegar a planos más profundos de la realidad.

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This paper reviews a study to analyze the number of times alphabet symbols occur in three commonly used basal reader series.

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We study complete continuity properties of operators onto ℓ2 and prove several results in the Dunford–Pettis theory of JB∗-triples and their projective tensor products, culminating in characterisations of the alternative Dunford–Pettis property for where E and F are JB∗-triples.

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The ship is the dominant element in the visual culture of the South Scandinavian Bronze Age, appearing in several different media, including rock carvings, decorated metalwork and above-ground monuments. Discussion has divided between those scholars who interpret this imagery in terms of long-distance exchange networks and those who emphasize its more local significance, including its deployment in mortuary ritual. A strikingly similar system is identified in Southeast Asia and part of Melanesia and can be interpreted through archaeological and ethnographic sources, but in this case there is no need to distinguish between 'practical' and 'symbolic' interpretations of the depictions of ships. This paper summarizes the evidence from this region and suggests that it can offer a fruitful source of comparison for archaeologists working in northern Europe.

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We solve an initial-boundary problem for the Klein-Gordon equation on the half line using the Riemann-Hilbert approach to solving linear boundary value problems advocated by Fokas. The approach we present can be also used to solve more complicated boundary value problems for this equation, such as problems posed on time-dependent domains. Furthermore, it can be extended to treat integrable nonlinearisations of the Klein-Gordon equation. In this respect, we briefly discuss how our results could motivate a novel treatment of the sine-Gordon equation.

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This paper investigates the application of the Hilbert spectrum (HS), which is a recent tool for the analysis of nonlinear and nonstationary time-series, to the study of electromyographic (EMG) signals. The HS allows for the visualization of the energy of signals through a joint time-frequency representation. In this work we illustrate the use of the HS in two distinct applications. The first is for feature extraction from EMG signals. Our results showed that the instantaneous mean frequency (IMNF) estimated from the HS is a relevant feature to clinical practice. We found that the median of the IMNF reduces when the force level of the muscle contraction increases. In the second application we investigated the use of the HS for detection of motor unit action potentials (MUAPs). The detection of MUAPs is a basic step in EMG decomposition tools, which provide relevant information about the neuromuscular system through the morphology and firing time of MUAPs. We compared, visually, how MUAP activity is perceived on the HS with visualizations provided by some traditional (e.g. scalogram, spectrogram, Wigner-Ville) time-frequency distributions. Furthermore, an alternative visualization to the HS, for detection of MUAPs, is proposed and compared to a similar approach based on the continuous wavelet transform (CWT). Our results showed that both the proposed technique and the CWT allowed for a clear visualization of MUAP activity on the time-frequency distributions, whereas results obtained with the HS were the most difficult to interpret as they were extremely affected by spurious energy activity. (c) 2008 Elsevier Inc. All rights reserved.

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Operator spaces of Hilbertian JC∗ -triples E are considered in the light of the universal ternary ring of operators (TRO) introduced in recent work. For these operator spaces, it is shown that their triple envelope (in the sense of Hamana) is the TRO they generate, that a complete isometry between any two of them is always the restriction of a TRO isomorphism and that distinct operator space structures on a fixed E are never completely isometric. In the infinite-dimensional cases, operator space structure is shown to be characterized by severe and definite restrictions upon finite-dimensional subspaces. Injective envelopes are explicitly computed.

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We study the homogeneous Riemann-Hilbert problem with a vanishing scalar-valued continuous coefficient. We characterize non-existence of nontrivial solutions in the case where the coefficient has its values along several rays starting from the origin. As a consequence, some results on injectivity and existence of eigenvalues of Toeplitz operators in Hardy spaces are obtained.

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This paper provides an overview of interpolation of Banach and Hilbert spaces, with a focus on establishing when equivalence of norms is in fact equality of norms in the key results of the theory. (In brief, our conclusion for the Hilbert space case is that, with the right normalisations, all the key results hold with equality of norms.) In the final section we apply the Hilbert space results to the Sobolev spaces Hs(Ω) and tildeHs(Ω), for s in R and an open Ω in R^n. We exhibit examples in one and two dimensions of sets Ω for which these scales of Sobolev spaces are not interpolation scales. In the cases when they are interpolation scales (in particular, if Ω is Lipschitz) we exhibit examples that show that, in general, the interpolation norm does not coincide with the intrinsic Sobolev norm and, in fact, the ratio of these two norms can be arbitrarily large.