1,720,964 research outputs found
σ-porous sets of generalised nonexpansive mappings
No full textIn the paper we show that many generic results obtained in the last 40 years in the field of fixed point theory, are consequences of one general theorem. As an application we get some extensions of them and we study the generic aspect of the existence of attractors of nonexpansive IFSs. We also give a detailed discussion on the relationship between two results obtained by De Blasi and Myjak, and Reich and Zaslavski
A comparison of two notions of porosity
No full textIn the paper we compare two notions of porosity: the R-ball porosity (R \rt 0) defined by Preiss and Zajı́ček, and the porosity which was introduced by Olevskii (here it will be called the O-porosity). We find this comparison interesting since in the literature there are two similar results concerning these two notions. We restrict our discussion to normed linear spaces since the R-ball porosity was originally defined in such spaces
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dichotomies for Lp spaces
No full textAbstractAssume that (X,Σ,μ) is a measure space and p1,…,pn, r>0. We prove that {(f1,…,fn)∈Lp1×⋯×Lpn:f1⋯fn∈Lr} is either Lp1×⋯×Lpn or a σ-porous subset of Lp1×⋯×Lpn. This dichotomy depends on properties of μ and the sign of the number 1r−1p1−⋯−1pn
Zero-dimensional compact metrizable spaces as attractors of generalized iterated function systems
No full textR.\ Miculescu and A.\ Mihail in 2008 introduced the concept of a \emph{generalized iterated function system} (GIFS in short), a particular extension of the classical IFS. The idea is that, instead of families of selfmaps of a metric space , GIFSs consist of maps defined on a finite Cartesian -th power with values in (in such a case we say that a GIFS is \emph{of order} ). It turned out that a great part of the classical Hutchinson theory has natural counterpart in this GIFSs' framework. On the other hand, there are known only few examples of fractal sets which are generated by GIFSs, but which are not IFSs' attractors. In the paper we study -dimensional compact metrizable spaces from the perspective of GIFSs' theory. Such investigations for classical IFSs have been undertaken in the last several years, for example by T.\ Banakh, E.\ D'Aniello, M.\ Nowak, T.H. Steele and F.\ Strobin. We prove that each such space is homeomorphic to the attractor of some GIFS on the real line. Moreover, we prove that can be embedded into the real line as {the attractor of some} GIFS of order and (in the same time) a nonattractor of any GIFS of order , as well as it can be embedded as a nonattractor of any GIFS. Then we show that a relatively simple modifications of deliver spaces whose each connected component is ``big'' and which are GIFS's attractors not homeomorphic with IFS's attractors. Finally, we use obtained results to show that a generic compact subset of a Hilbert space is not the attractor of any Banach GIFS
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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