106,370 research outputs found
The Tuza–Vestergaard Theorem
No full textThe transversal number τ(H) of a hypergraph H is the minimum number of vertices that intersect every edge of H. A 6-uniform hypergraph has all edges of size 6. On 10 November 2000 Tuza and Vestergaard [Discuss. Math. Graph Theory, 22 (2002), pp. 199-210] conjectured that if H is a 3-regular 6-uniform hypergraph of order n, then τ(H) ≤ 1/4n. In this paper we prove this conjecture, which has become known as the Tuza-Vestergaard conjecture.</p
Extensions and applications of the Tuza-Vestergaard theorem
No full textThe transversal number τ(H) of a hypergraph H is the minimum number of vertices that intersect every edge of H. A 6-uniform hypergraph has all edges of size 6. On 10 November 2000 Tuza and Vestergaard (2002) conjectured that if H is a 3-regular 6-uniform hypergraph of order n, then [Formula presented]. This conjecture was recently proven by the Henning and Yeo (2023) and is now called the Tuza-Vestergaard Theorem. In this paper we extend the Tuza-Vestergaard Theorem by relaxing the 3-regularity constraint and allowing bounded maximum degree 4. We present several applications of the Tuza-Vestergaard Theorem and its extension. We obtain best known upper bounds to date on the transversal number of a (general) 6-uniform hypergraph H of order n and size m. In particular, if H is a 4-regular 6-uniform hypergraph of order n, then we show that [Formula presented]. The Tuza constant c6 is defined by [Formula presented], where the supremum is taken over the class of all 6-uniform hypergraphs H. Since 1990 the exact value of c6 has yet to be determined. We show that [Formula presented], where [Formula presented] is conjectured to be the correct bound. Moreover we show that if G is a graph of order n with δ(G)≥6, then [Formula presented], where γt(G) denotes the total domination number of G and [Formula presented] is conjectured to be the correct bound. These bounds improve best known bounds to date.</p
Could Trump and Xi break the deadlock in the World Bank?
No full textJakob Vestergaard and Robert H. Wade argue that Trump’s transactional approach to deals might paradoxically help break the long-standing deadlock in World Bank governance by pushing China to increase its financial contributions in exchange for greater shareholding and influence
World Bank governance reform:“Puppet on a string”?
No full textThe Annual Meetings of the World Bank and the Fund will be held in Washington DC the week of October 21 – 26, 2024. The BRICS+ summit will be held in Kazan, Russia, October 22 – 24. The G20 summit will be held in Rio, November 18-19. Robert H. Wade and Jakob Vestergaard argue that the issues discussed in this short essay should be on participants' agendas with a note recommending preferential treatment
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
No full textWe 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
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Efficacy and safety of small incision lenticule extraction (SMILE) – a retrospective quality control study from a University hospital clinic
No full textTitle: Efficacy and safety of small incision lenticule extraction (SMILE) – a retrospective quality control study from a University hospital clinicAnders H. Vestergaard, MD, PhD, Department of Ophthalmology, Odense University Hospital, Denmark.Purpose: To evaluate the safety and efficacy of the SMILE procedure for treatment of moderate to high de-grees of myopia and low to moderate degrees of astigmatism.Setting: Department of Ophthalmology, Odense University Hospital, Denmark.ConclusionsIn this retrospective real-life evaluation study, we found that SMILE was a safe and efficient procedure for all degrees of myopia and myopic astigmatism. Refractive precision was high, and the main reason for impaired postoperative vision was related to corneal dryness.Final disclosure: The Region of Southern Denmark has supported this project.<br/
Contribution of Information and Communication Technology (ICT) in Country’S H-Index
No full textThe aim of this study is to examine the effect of Information and Communication Technology (ICT) development on country’s scientific ranking as measured by H-index. Moreover, this study applies ICT development sub-indices including ICT Use, ICT Access and ICT skill to find the distinct effect of these sub-indices on country’s H-index. To this purpose, required data for the panel of 14 Middle East countries over the period 1995 to 2009 is collected. Findings of the current study show that ICT development increases the H-index of the sample countries. The results also indicate that ICT Use and ICT Skill sub-indices positively contribute to higher H-index but the effect of ICT access on country’s H-index is not clear
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