1,720,976 research outputs found
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
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
Tractable Databases: How to Make Propositional Unit Resolution Complete through Compilation
No full textWe present procedures to compile any propositional clausal database \Sigma into a logically equivalent "compiled" database \Sigma ? such that, for any clause C, \Sigma j= C if and only if there is a unit refutation of \Sigma ? [ :C. It follows that once the compilation process is complete any query about the logical consequences of \Sigma can be correctly answered in time linear in the sum of the sizes of \Sigma ? and the query. The compiled database \Sigma ? is for all but one of the procedures a subset of the set P I (\Sigma) of prime implicates of \Sigma, but \Sigma ? can be exponentially smaller than P I (\Sigma). Of independent interest, we prove the equivalence of unit-refutability with two restrictions of resolution, and provide a new sufficient condition for unit refutation completeness, thus identifying a new class of tractable theories, one which is of interest to abduction problems as well. Finally, we apply the results to the design of a complete LTMS. 1 INTRODUCT..
An Analysis of Approximate Knowledge Compilation
No full textKnowledge compilation is the process by which an initial theory \Sigma with respect to which inference is intractable is transformed into one or more "approximate" or equivalent theories with respect to which inference can be performed efficiently. Selman and Kautz introduced Horn lowest upper bound (LUB) approximations in [ SK91 ] , and generalized them in [ KS91; SK95 ] to a number of target languages other than Horn. In this paper, we analyze the problem of knowledge compilation for arbitrary clausal target languages, generalizing in several ways previous results. We provide general characterizations of the LUB that are independent of the target language; analyze the properties of the Generate-LUB algorithm of Selman and Kautz, proving its correctness for any target language closed under subsumption (including a wide family of languages which guarantee polynomial size approximations); and generalize the procedure to arbitrary target languages. We also examine some computational aspe..
Computing Knowledge Base Updates
No full textWe present syntactic characterizations of propositional update operators based in the PMA approach [ Winslett, 1988a, Winslett, 1988b ] ), and develop algorithms for computing the updated database on the basis of this characterization. Unlike any other previous work in this area, the methods presented here do not require direct manipulation or explicit storage of complete models of the database. They also appear to be easily extensible to other update operators based in the idea of minimal change. 1 INTRODUCTION Much recent work has been devoted to giving accounts of belief revision based on the work of Alchourr 'on, Gardenfors and Makinson ( [ Alchourr'on et al., 1985 ] , [ Gardenfors, 1988 ] , [ Gardenfors and Makinson, 1988 ] ), who try to formalize the notion of a minimal belief change through a set of postulates that every revision operator should satisfy. [ Katsuno and Mendelzon, 1991 ] recently suggested that revision is not the only way in which new information can be incorpor..
Reasoning about Default Persistence
No full textLifschitz [ 1990 ] introduced the predicate frame in formal theories of action as a way of limiting the "common sense law of inertia" to certain designated fluents. This idea was adopted in [ Lin and Shoham, 1991 ] , and extended in [ del Val and Shoham, 1993 ] so as to provide a very general analysis of the closely related problem of belief update. The predicate, renamed persistent in [ del Val and Shoham, 1993 ] , provides a means for the explicit axiomatization of assumptions about which facts should "persist by default" when actions are performed. This paper demonstrates the need for, and the power and flexibility of this kind of explicit control of default assumptions about what should or should not change as a result of an action, with special emphasis on the problem of indeterministic actions, for which we provide the first circumscriptive solution. 1 Introduction The idea of assuming that, "by default," facts tend to persist into the future has been at the basis of most attemp..
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