1,721,023 research outputs found
Combinatorial problems in solving linear systems
Get PDFNumerical linear algebra and combinatorial optimization are vast
subjects; as is their interaction. In virtually all cases there should
be a notion of sparsity for a combinatorial problem to arise. Sparse
matrices, therefore, form the basis of the interaction of these two
seemingly disparate subjects. As the core of many of today's numerical linear
algebra computations consists of sparse linear system solutions, we
will cover combinatorial problems, notions, and algorithms relating to
those computations.
This talk is thus concerned with direct and iterative methods for sparse
linear systems and their intercation with combinatorial optimization.
On the direct methods side, we discuss matrix ordering; bipartite matching
and matrix scaling for better pivoting; task assignment and scheduling
for parallel multifrontal solvers. On the iterative method side, we discuss
preconditioning techniques including incomplete factor preconditioners
(notion of level of fill-in), support graph preconditioners (graph
embedding concepts), and algebraic multigrids (independent sets in
undirected graphs).
In a separate part of the talk, we discuss methods that aim to exploit
sparsity during linear system solution. These methods include block
diagonalization of the matrix; efficient triangular system solutions
for right-hand side vectors of single nonzero entries. Towards the
end, we mention, quite briefly as they are topics of other invited
talks, some other areas whose interactions with combinatorial
optimization are of great benefit to numerical linear algebra. These
include graph and hypergraph partitioning for load balancing problems,
and colouring problems in numerical optimization. On closing, we
compile and list a set of open problems
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
A brief bibliography of recent research and software for the parallel solution of large sparse linear equations
No full textWe give some pointers to recent work on the parallel solution of sparse linear equations. We consider both iterative and direct methods and combinations of these two approaches and list some Web sites where software may be found. Keywords: sparse linear systems, sparse least squares, sparse normal equations, mixed model equations, BLUP, cattle breeding, iterative methods, direct methods, preconditioning, block iterative methods. AMS(MOS) subject classifications: 65F05, 65F50. 1 Current reports available at http://www.cerfacs.fr/algor/algo reports.html. This short report was produced by request after a keynote talk presented by the author at an international conference on Computational Cattle Breeding, held in Helsinki, Finland on 19th and 20th March 1999. 2 [email protected]. Also at Atlas Centre, RAL, Oxon OX11 0QX, England. Contents 1 Introduction 1 2 Iterative methods 1 3 Direct methods 1 4 Solution of least-squares problems 2 5 Methods coupling direct and iterative techniques ..
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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