1,720,966 research outputs found
Joining caterpillars and stability of the tree center
No full textAbstractThe path-table P(T) of a tree T collects information regarding the paths in T: for each vertex v, the row of P(T) relative to v lists the number of paths containing v of the various lengths. We call this row the path-row of v in T.Two trees having the same path-table (up to reordering the rows) are called path-congruent (or path-isomorphic).Motivated by Kelly–Ulam's Reconstruction Conjecture and its variants, we have looked for new necessary and sufficient conditions for isomorphisms between two trees.Path-congruent trees need not be isomorphic, although they are similar in some respects. In [P. Dulio, V. Pannone, Trees with path-stable center, Ars Combinatoria, LXXX (2006) 153–175] we have introduced the concepts of trunk Tr(T) of a tree T and ramification ramv of a vertex v∈V(Tr(T)), and proved that, if the ramification of the central vertices attains its minimum or maximum value, then the path-row of a central vertex is “unique”, i.e. it is different from the path-row of any non-central vertex (in fact, this uniqueness property of a central path-row holds for all trees of diameter less than 8, regardless of the ramification values).In this paper we prove that, for all other values of the ramification, and for all diameters greater than 7, there are trees in which the above uniqueness fails
The converse of Kelly’s lemma and control-classes in graph reconstruction
Full text linksummary:We prove a converse of the well-known Kelly’s Lemma. This motivates the introduction of the general notions of -table, -congruence and control-class
Trees with the same path-table
Full text linkAs a generalization of isomorphisms of graphs, we consider path-congruences, that is maps which preserve the number of paths of any length.We construct families of pairs of non-isomorphic trees with the same path-table.<br /
38th Annual meeting of the European Society for Pediatric Gastroenterology hepatology and Nutrition. Porto, Portugal, June 1-4, 2005. Osteoporosis and inflammatory bowel disease (IBD) in children: Variables affecting bone mineral density (BMD). M. Paganelli, C Albanese, m Cirulli, V La balestra, V Pannone, R Passariello, S Cucchiara. J Pediatr Gastr Nutr 40:644, PG2-12, 2005
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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
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