1,720,958 research outputs found
Tropical Poincaré duality spaces
No full textCertain polyhedral fans can be constructed from matroids, and these serve as the local model of tropical manifolds. Such matroidal fans satisfy a tropical version of Poincaré duality [JRS17]. In this thesis, we give conditions on pure polyhedral fans which are equivalent to this property. Moreover, we classify tropical Poincaré spaces of dimension two. Furthermore, we develop the derived category of cellular sheaves on a polyhedral complex, based on work by Curry [Cur14], and use Verdier duality to prove a vanishing result on the compact support cohomology of the wave sheaf on a Cohen--Macaulay simplicial polyhedral fan
Tropicalization of curve arrangement complements and arroids
No full textWe define arroids as an abstract axiom set encoding the intersection properties of arrangements of curves. The tropicalization of the complement of an arrangement of curves meeting pairwise transversely is shown to be determined by the associated arroid. We give conditions for when the cohomology of the complement of an arrangement is computable using tropical cohomology, and we give criteria for when the complement is a maximal variety in terms of tropical geometry
Tropicalization of curve arrangement complements and arroids
Get PDFWe define arroids as an abstract axiom set encoding the intersection
properties of arrangements of curves. The tropicalization of the complement of
arrangement of curves meeting pairwise transversely is shown to be determined
by the associated arroid. We give conditions for when the cohomology of the
complement of an arrangement is computable using tropical cohomology, and we
give criteria for when the complement is a maximal variety in terms of tropical
geometry.Comment: 22 pages, 6 figures, comments welcome
Tropical Poincar\'e duality spaces
Get PDFThe tropical fundamental class of a rational balanced polyhedral fan induces
cap products between tropical cohomology and tropical Borel-Moore homology.
When all these cap products are isomorphisms, the fan is said to be a tropical
Poincar\'e duality space. If all the stars of faces also are such spaces, such
as for fans of matroids, the fan is called a local tropical Poincar\'e duality
space.
In this article, we first give some necessary conditions for fans to be
tropical Poincar\'e duality spaces and a classification in dimension one. Next,
we prove that tropical Poincar\'e duality for the stars of all faces of
dimension greater than zero and a vanishing condition implies tropical
Poincar\'e duality of the fan. This leads to necessary and sufficient
conditions for a fan to be a local tropical Poincar\'e duality space. Finally,
we use such fans to show that certain abstract balanced polyhedral spaces
satisfy tropical Poincar\'e duality.Comment: 29 pages, 6 figure
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
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