1,721,024 research outputs found
Courier assignment in meal delivery via integer programming: A case study in Rome
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Network design with a discrete set of traffic matrices
No full textIn this paper, we deal with network design problems in which we are given a finite set of possible traffic matrices. We settle some questions about the computational complexity of this problem. We also show that, unless P=NP, there is no polynomial-time approximation scheme even on ring networks, a special case that has received considerable attention for a variety of related problems. However, for such networks, we provide a 43-approximation algorithm, and an exact polynomial-time algorithm for the single source case. © 2013 Elsevier B.V. All rights reserved
Minimum weighted clique cover on claw‐free perfect graphs
No full textThe first combinatorial algorithm for the minimum weighted clique cover (MWCC) in a claw-free perfect graph due to Hsu and Nemhauser dates back to 1984. It is essentially a ``dual´´ algorithm as it relies on any algorithm for the maximum weighted stable set (MWSS) problem in claw-free graphs and, taking into account the best known complexity for the latter problem, its complexity is . More recently, Chudnovsky and Seymour introduced a composition operation, strip-composition, in order to define their structural results for claw-free graphs; however, this composition operation is general and applies to non-claw-free graphs as well. In this paper, we show that a MWCC of a perfect strip-composed graph, with the basic graphs belonging to a class , can be found in polynomial time, provided that the mwcc problem can be solved on in polynomial time. For the case of claw-free perfect strip-composed graphs, the algorithm can betailored so that it never requires the computation of a MWSS on the strips and can be implemented as to run in time. Finally, building upon several results from the literature, we show how to deal with non-strip-composed claw-free perfect graphs, and therefore compute a MWCC in a general claw-free perfect graph in time.Fil: Bonomo, Flavia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigación en Ciencias de la Computación. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigación en Ciencias de la Computación; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Computación; ArgentinaFil: Oriolo, Gianpaolo. Universita Tor Vergata; ItaliaFil: Snels, Claudia. Universita Tor Vergata; Itali
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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