Locally linear approximation for Kernel methods : the Railway Kernel

In this paper we present a new kernel, the Railway Kernel, that works properly for general (nonlinear) classification problems, with the interesting property that acts locally as a linear kernel. In this way, we avoid potential problems due to the use of a general purpose kernel, like the RBF kernel, as the high dimension of the induced feature space. As a consequence, following our methodology the number of support vectors is much lower and, therefore, the generalization capability of the proposed kernel is higher than the obtained using RBF kernels. Experimental work is shown to support the theoretical issues

Representing functional data in reproducing Kernel Hilbert Spaces with applications to clustering and classification

Functional data are difficult to manage for many traditional statistical techniques given their very high (or intrinsically infinite) dimensionality. The reason is that functional data are essentially functions and most algorithms are designed to work with (low) finite-dimensional vectors. Within this context we propose techniques to obtain finitedimensional representations of functional data. The key idea is to consider each functional curve as a point in a general function space and then project these points onto a Reproducing Kernel Hilbert Space with the aid of Regularization theory. In this work we describe the projection method, analyze its theoretical properties and propose a model selection procedure to select appropriate Reproducing Kernel Hilbert spaces to project the functional data.Functional data, Reproducing, Kernel Hilbert Spaces, Regularization theory

Role Playing as a Strategy in Teaching - Learning English for the Development of Speaking Skills in High School Students

Contiene gráficos anexosAunque desde el enfoque comunicativo el role playing como estrategia para el desarrollo de habilidades orales en los estudiantes de idiomas ya se ha propuesto, ya que les permite practicar la comunicación en diferentes contextos sociales mediante la interpretación de roles, esta técnica no ha sido ampliamente utilizada por los profesores de secundaria en sus clases de idiomas, relegándola a una actividad secundaria a ser usada cuando la clase se vuelve monótona o simplemente para explorar algunas de las expresiones orales de los estudiantes. Una de las causas de esta situación es que muchos profesores no conocen las directrices específicas que permitan su aplicación concreta y efectiva. El presente documento tiene como objetivo identificar las principales características y lineamientos de la técnica de role playing en el desarrollo de las habilidades de habla inglesa en los estudiantes de secundaria. A través de una revisión de la literatura propuesta por diferentes autores, esta monografía tiene como objetivo reconocer las características del role playing como estrategia de enseñanza-aprendizaje y analizar su relación con el desarrollo de las habilidades de habla inglesa. Este documento también busca compilar algunos ejemplos de actividades de role playing para el desarrollo de las habilidades orales en inglés que sirvan como referencia a aquellos profesores de secundaria que quieran implementarla de manera concreta y efectiva en su aula de idiomas.Student, Ricardo G., Role playing as strategy for development of speaking skills in high school students. Licenciatura en inglés como Lengua Extranjera, November, 2020, Universidad Nacional Abierta y a Distancia. Although from the communicative approach role playing technique as a useful strategy for the development of speaking skills in language students has been proposed since it allows them to practice communication in different social contexts by playing different roles, this technique has not been widely used by secondary school teachers in their language classrooms, relegating it as a secondary activity to be used when the class becomes monotonous or simply to explore some of the students' oral expressions. One of the causes of this situation is that many teachers are unaware of the specific guidelines that allow for its concrete and effective application. This document aims to identify the main characteristics and guidelines of role playing in the development of English-speaking skills in high school students. Through a review of the literature by different authors, this monograph aims to recognize the characteristics of role playing as a teaching-learning strategy and to analyze its relationship with the development of English-speaking skills. Finally, this paper aims to collect some samples of role-playing activities for the development of English oral skills that serve as a reference for the secondary school teachers who want to implement this technique in a concrete and effective way in their language classroom

The resolving number of a graph

We study a graph parameter related to resolving sets and metric dimension, namely the resolving number, introduced by Chartrand, Poisson and Zhang. First, we establish an important difference between the two parameters: while computing the metric dimension of an arbitrary graph is known to be NP-hard, we show that the resolving number can be computed in polynomial time. We then relate the resolving number to classical graph parameters: diameter, girth, clique number, order and maximum degree. With these relations in hand, we characterize the graphs with resolving number 3 extending other studies that provide characterizations for smaller resolving number.Comment: 13 pages, 3 figure

Global properties of the spectrum of the Haldane-Shastry spin chain

We derive an exact expression for the partition function of the su(m) Haldane-Shastry spin chain, which we use to study the density of levels and the distribution of the spacing between consecutive levels. Our computations show that when the number of sites N is large enough the level density is Gaussian to a very high degree of approximation. More surprisingly, we also find that the nearest-neighbor spacing distribution is not Poissonian, so that this model departs from the typical behavior for an integrable system. We show that the cumulative spacing distribution of the model can be well approximated by a simple functional law involving only three parameters.Comment: RevTeX 4, 7 pages, 4 figures. To appear in Phys. Rev.

Resolving sets for breaking symmetries of graphs

This paper deals with the maximum value of the difference between the determining number and the metric dimension of a graph as a function of its order. Our technique requires to use locating-dominating sets, and perform an independent study on other functions related to these sets. Thus, we obtain lower and upper bounds on all these functions by means of very diverse tools. Among them are some adequate constructions of graphs, a variant of a classical result in graph domination and a polynomial time algorithm that produces both distinguishing sets and determining sets. Further, we consider specific families of graphs where the restrictions of these functions can be computed. To this end, we utilize two well-known objects in graph theory: $k$-dominating sets and matchings.Comment: 24 pages, 12 figure

Determinants of organizational form: Transaction costs and institutions in the European trucking industry

We explain why European trucking carriers are much smaller and rely more heavily on owner-operators (as opposed to employee drivers) than their US counterparts. Our analysis begins by ruling out differences in technology as the source of those disparities and confirms that standard hypotheses in organizational economics, which have been shown to explain the choice of organizational form in US industry, also apply in Europe. We then argue that the preference for subcontracting over vertical integration in Europe is the result of European institutions—particularly, labor regulation and tax laws—that increase the costs of vertical integration.Transaction costs, governance, hybrids, transportation

Catalogación y análisis de los sistemas de envolvente neumática, a través del estudio de sus principales parámetros cualitativos

El diseño de sistemas neumáticos como envolvente arquitectónica ha experimentado un importante desarrollo, desde que a principios del s.XX las nuevas necesidades militares, sociales y económicas requirieran nuevos sistemas para la cubrición de grandes luces, con un rápido y fácil montaje. Sin embargo, los múltiples proyectos y experiencias, se han desarrollado sin una línea constante de documentación y catalogación. Su revisión histórica y crítica, a través de artículos y publicaciones especializadas, ha mantenido un ciclo paralelo al interés global mostrado por este tipo de sistemas constructivos; apareciendo picos de máxima desarrollo, como el de los años setenta, y valles de escasa documentación como el de décadas posteriores. La investigación ha tenido como objetivo la realización de una nueva revisión histórica y crítica de esta todavía “joven” tecnología, complementando los periodos de menor catalogación y permitiendo establecer los condicionantes principales y los puntos de afianzamiento y de inflexión, desarrollados en el ámbito de los sistemas de envolvente neumática arquitectónica. La metodología de análisis se ha focalizado en la localización y documentación de aquellos proyectos, tanto construidos como conceptuales, cuyas propiedades cualitativas hayan supuesto una especial innovación en el ámbito de las tecnologías de envolvente neumática. De modo que sobre cada una de las estrategias catalogadas, se ha procedido al estudio pormenorizado de sus parámetros morfológicos, funcionales, constructivos, energéticos y medioambientales. La metodología de organización de datos, se ha coordinado a través de la realización de una base de datos de carácter interactiva y abierta, facilitanto tanto el estudio individualizado de cada una de las propuestas, como el análisis comparativo de los diferentes proyectos, en función de los diferentes parámetros y subparámetros de caracterización. La catalogación de más de 660 estrategias, ha permitido el estudio comparativo y evolutivo de las principales tipologías neumáticas; a través de un sistema organizativo de código abierto, que ha facilitado una lectura de resultados no lineal, interactiva y dinámica