1,720,963 research outputs found
A unifying approach to solve some classes of rank-three multiplicative and fractional programs involving linear functions
No full textOn discrete quasiconvexity concepts for single variable scalar functions
No full textThe aim of this paper is to propose quasiconvexity concepts for discrete single variable functions and state some related optimality conditions. Four classes of discrete quasiconvex single variable functions are introduced, compared and characterized. Two different algorithm procedures for determining a minimum are provided
Solving linear multiplicative programs via branch-and-bound: a computational experience
Get PDFIn this paper, linear multiplicative programs are approached with a branch-and-bound scheme and a detailed computational study is provided. Several underestimation functions are analyzed and various partitioning criteria are presented. A particular class of linear multiplicative programs, useful to solve some applicative bilevel problems, is considered from a theoretical point of view to emphasize an efficient solution method. Detailed results of the computational study are provided to point out the performances provided by using various underestimation functions and partitioning criteria, thus improving some of the results of the current literature
A statistical model for the dynamics between two fuzzy states: theory and application to poverty analysis
No full textManifestations of a number of social and economic phenomena are commonly perceived as dichotomous: welfare-poverty, employment-unemployment, health-illness, etc.. However these phenomena are intrinsically fuzzy, therefore a statistical analysis with binary variables oversimplifies reality and tends to wipe out all the nuances that exist between the two opposite extremes. Such a problem is especially relevant in the case of dynamic analyses on panel data, where the use of binary variables is required if one of the available discrete states models is to be applied. In order to avoid such a rigid simplification it is possible to follow a fuzzy approach which is coherent with the intrinsic nature of the studied phenomenon. This paper deals with the dynamic model with fuzzy states recently proposed and developed in a series of papers (Cheli, 1995; Cheli and Betti, 1999; Betti, Cheli and Lemmi 2002). Here we basically aim to summarise its theory and to develop it by means of a series of theorems and by introducing two new statistical tools that we called Dynamic Indices and Average Transition Matrices. Although the scope of this paper is essentially methodological, we also present an application to the analysis of poverty dynamics in Great Britain from 1991 to 1997
Theoretical and algorithmic results for a class of hierarchical fleet mix problems
No full textIn this paper a workforce model is studied from both a theoretical and an algorithmic point of view. In the considered hierarchical model workforce units can be substituted by higher qualified ones; external workforce can also be hired to cover low qualified jobs. An exact recursive solution algorithm is proposed to solve the problems and its efficiency is improved by means of cut conditions and discrete convexity properties. Finally, the results of a computational test are provided. (C) 2008 Elsevier B.V. All rights reserved
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
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