1,721,221 research outputs found
Typical convex programming problem is very well posed
No full textIn this paper we consider the collection of convex programming problems with inequality and
equality constraints, in which every problem of the collection is obtained by linear perturbations of the cost
function and right-hand side perturbation of the constraints, while the “core” cost function and the left-hand
side constraint functions are kept fixed. The main result shows that the set of the problems which are not
well-posed is σ-porous in a certain strong sense. Our results concern both the infinite and finite dimensional
case. In the last case the conclusions are significantly sharper
On Limits of Variational Problems. The case of a Non-Coercive Functional
No full textTypical convergence theorems for value functions and solutions of (parametric families of)
optimization problems based on È-convergence of the corresponding functionals usually
rely on equi-coercivity assumptions. Without them the connection between the È-limit of
the functionals and values and/or solutions of the problems may be completely broken.
The question to be discussed is whether it is possible, even in the absence of a coercivity-
type assumption, to ßnd limiting optimization problems (parametrized in a similar way
and determined by functionals which may diÞer from the È-limits of the functionals of
the sequence) such that the value functions and solutions of the problems of the sequence
converge in a certain sense to those of the limiting problems. A positive answer to the
question is given to a class of variational problems (containing optimal control problems
with linear dynamics)
Almost every convex or quadratic problem is well posed
No full textAn abstract principle is introduced, aimed at proving that classes of optimization problems are typically well posed in
the sense that the collection of ill-posed problems within each class is a-porous. As a consequence, we establish
typical well-posedness in the above sense for unconstrained minimization of certain classes of functions (e.g.,
convex and quasi-convex continuous), as well as of convex programming with inequality constraints. We conclude
the paper by showing that the collection of consistent ill-posed problems of quadratic programming of any fixed
size has Lebesgue measure zero in the corresponding Euclidean spac
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
- …
