66,791 research outputs found
Sobre la no convergencia del método de mínimos cuadrados en dimensión infinita
No full textUn procedimiento muy utilizado en diversas aplicaciones para aproximarlas soluciones de un problema inverso infinito-dimensional de la formaAx=b, dondeAes un operador lineal y compacto sobre un cierto espacio de HilbertXybes eldato dado, consiste en encontrar una sucesi ́on{XN}de subespacios aproximantes finito-dimensionales deXcuya uni ́on es densa enXy construir la sucesi ́on{xN}de solucionesde m ́ınimos cuadrados del problema en cada subespacioXN. En [3], Seidman demostr ́oque si el problema es mal condicionado, entonces sin ninguna hip ́otesis adicional sobrela soluci ́on exacta o sobre la sucesi ́on de subespacios aproximantes{XN}, no se puedegarantizar que la sucesi ́on{xN}converger ́a a la soluci ́on exacta. En este art ́ıculo seextiende este resultado: se prueba que siXes separable, entonces para cualquierb∈X,b6= 0, y para cualquier funci ́on no negativa definida sobre los naturalesf: IN→IR+,existe un operador lineal, compacto e inyectivoAy una sucesi ́on creciente de subespaciosfinito-dimensionalesXN⊂Xtales que∥∥xN−A−1b∥∥≥f(N) para todoN∈IN, dondexNes la soluci ́on de m ́ınimos cuadrados del problemaAx=benXN.Fil: Spies, Ruben Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Matemática Aplicada del Litoral. Universidad Nacional del Litoral. Instituto de Matemática Aplicada del Litoral; ArgentinaFil: Temperini, Karina Guadalupe. Universidad Nacional del Litoral; Argentin
The use of e-learning methodologies and technologies for generating personalised tours in cultural heritage environments
No full textThis work addresses the issue of personalised tours in cultural heritage domains, by exploiting methods and techniques developed for e-learning, in particular those that regard personalised e-learning courses. The main idea of our work is that a tour in a museum or in an archaeological site, either fully virtual or blended, may be managed through an e-learning environment. We propose the use of the LECOMPS5, an e-learning environment, to provide museums or other cultural sites with the capability of automatically planning personalised tours, according to visitors' needs and interests. We also show an example of an application of this system to an ancient archaeological site called Lucus Feroniae, showing how an e-learning platform can be successfully used for guiding visitors
Virtual Cultural Tour Personalization by means of an Adaptive E-Learning System: a Case Study
No full textVisiting a real or virtual museum or an archaeological site
can be a hard task, especially in case of large sites provided with many
works of art or ancient ruins. For this reason most historical sites provide
guided tours, to improve visitors satisfaction and interest. In this
work we explore the use of an e-learning environment, called Lecomps5,
to provide museums or other cultural sites with the capability of automatically
planning personalized tours, according to visitors needs and
interests. Lecomps5 allows a domain expert, through a suitable GUI, to
build a pool of learning components concerning a given site. Then the
system, by means of an embedded planner, generates a personalized tour
through the works of art, on the basis of the visitor’s artistic interests and
needs. We propose a first application of this system to an ancient archaeological
site called Lucus Feroniae, showing how an e-learning platform
can be successfully used for guiding visitors as well
K-OpenAnswer: a simulation environment to analyze the dynamics of massive open online courses in smart cities
No full textThe smartness of a city is given by the technologies it put to use, and more than that, by the people empowered by such technologies; it is worth thinking about how people can be trained to be empowered by smart technologies, and how cities can become “educational.” So, while sustainability and technology solutions for smart cities are strategic challenges, one of these is surely distance education and training. In this field, the Web offers many opportunities, such as the e-learning platforms where students can learn, according to their own needs and pace. The massive open online courses (MOOCs) are particular distance learning platforms, generally offering, so far, free courses on a huge amount of topics, and characterized by a (potentially) very high number of enrollments. In a MOOC, a teacher, or tutor, has a hard life when trying to follow and manage with the learning processes of thousands of students. In particular, assessment can be managed almost exclusively by letting the student answer questions in closed answers tests. This strategy has some didactic limits, while a valid alternative is to use peer assessment (PA) over more articulated assessment activities (e.g., open-ended questions). PA makes students grade their peers’ answers, and provides learners with significant advantages, such as refining their knowledge of the subject matter, and developing their meta-cognitive skills. In this work, we present a software platform called K-OpenAnswer, which helps teachers to simulate the dynamic of a MOOC where PA is used. The system uses a machine learning technique, based on a modified version of the K-NN algorithm, and provides teachers with a statistical environment by which they can monitor the evolving dynamic of a simulated MOOC, according to the techniques we use to implement PA. An experimental evaluation is presented that highlights the advantages of using the system as a valid tool for the study of real MOOCs
Goals and benchmarks for automated map reasoning
No full textAbstractTarski–Givant’s map calculus is briefly reviewed, and a plan of research is outlined aimed at investigating applications of this ground equational formalism in the theorem-proving field. The main goal is to create synergy between first-order predicate calculus and the map calculus. Techniques for translating isolated sentences, as well as entire theories, from first-order logic into map calculus are designed, or in some cases simply brought nearer through the exercise of specifying properties of a few familiar structures (natural numbers, nested lists, finite sets, lattices). It is also highlighted to what extent a state-of-the-art theorem-prover for first-order logic, namely Otter, can be exploited not only to emulate, but also to reason about, map calculus. Issues regarding “safe" forms of map reasoning are singled out, in sight of possible generalizations to the database area
Configuration of Personalized e-Learning Courses in Moodle
No full textOur work carries on the idea of configuring
personalized courses by means of automated planning techniques,
preserving coherence with present standards for elearning,
in particular with SCORM properties.
Starting from a previous prototype based on suitably
defined learning objects, learning components, we intend to
make it available in a wider contest. To this aim we design
a mapping between our learning component specification
and the definition of a SCO, a SCORM 1.2 compliant
learning object. In this way we can extend conservatively
the usual SCO by enriching it with those elements that are
relevant for the process of automated configuration: while
the original SCORM properties stay unchanged, we can
then make course configuration with a SCORM compliant
learning object. In order to obtain such a mapping, the
ScormUni tag format has been devised, which is an
extension of SCORM meta data. We show here how the
above mentioned prototype has evolved into UniTag , a
software module that extends Moodle (Version 1.6)
Multicomponent and Metal-Free Diels–Alder/Aromatization Approach to the Stereospecific Synthesis of E-(Hetero)Stilbenes and Diarylacetylenes
No full textHerein, we present a novel and metal-free approach to the stereospecific synthesis of E-stilbenes. Starting from substituted 6-arylhexa-3,5-dien-2-ones, a multicomponent enolacetylation/intermolecular Diels-Alder reaction was performed using ethyl acetate as a green solvent. The obtained cycloadducts were then oxidized without purification to produce the stilbenic products in good yields (up to 67%) and with complete (E)-stereospecificity and regioselectivity. Moreover, heterostilbenes were synthetized using this approach, displaying the potential applications of this protocol in pharmaceutical and material sciences. The proposed methodology was further extended to the synthesis of diarylacetylenes, furnishing a new metal-free synthetic access to this important class of compounds. Furthermore, DFT calculations were performed confirming a concerted [4+2] reaction mechanism of the key ring-forming step. At last, the energetic analysis of the possible Transition States helps to shed some light on the experimentally observed total regio- and chemoselectivit
Layered map reasoning An experimental approach put to trial on sets1 1This research was partially funded by the Italian IASI-CNR (coordinated project log(SETA)) and by MURST (PGR-2000—Automazione del ragionamento in teorie insiemistiche).
No full textAbstractNew successes in dealing with set-theories by means of state-of-the-art theorem-provers may ensue from terse and concise axiomatic systems, such as can be moulded in the framework of the (fully equational) Tarski-Givant formalism of dyadic relations, here named ‘maps’. This paper sets the ground for systematic experimentation based on such axiomatic systems. On top of a kernel axiomatization of map algebra, we develop a layered formalization of basic set-theoretic concepts. A number of concrete experiments have been carried out in this framework, as the paper reports, with the assistance of a first-order theorem-prover. The aim is to assess the potential usefulness of the proposed layered architecture and, to the extent it reveals promising, to best tune it
A framework to support social-collaborative personalized e-learning
No full textWe propose a comprehensive framework to support the personalization and adaptivity of courses in e-learning environments where the traditional activity of individual study is augmented by social-collaborative and group based educational activities. The framework aims to get its pedagogical significance from the Vygotskij Theory; it points out a minimal set of requirements to meet, in order to allow its implementations based on modules possibly constituted by independent e-learning software systems, all collaborating under a common interface. © 2013 Springer-Verlag
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