1,721,033 research outputs found
Gelfand models and Robinson–Schensted correspondence
No full textIn F. Caselli (Involutory reflection groups and their models, J. Algebra
24:370–393, 2010), a uniform Gelfand model is constructed for all nonexceptional
irreducible complex reflection groups which are involutory. Such models can be
naturally decomposed into the direct sum of submodules indexed by Sn-conjugacy
classes, and we present here a general result that relates the irreducible decomposition of these submodules with the projective Robinson–Schensted correspondence.
This description also reflects, in a very explicit way, the existence of split representations for these groups
Refined Gelfand models for wreath products
No full textAbstractIn [F. Caselli, Involutory reflection groups and their models, J. Algebra 24 (2010), 370–393] there is constructed a uniform Gelfand model for all non-exceptional irreducible complex reflection groups which are involutory. This model can be naturally decomposed into the direct sum of submodules indexed by symmetric conjugacy classes, and in this paper we present a simple combinatorial description of the irreducible decomposition of these submodules if the group is the wreath product of a cyclic group with a symmetric group. This is attained by showing that such decomposition is compatible with the generalized Robinson–Schensted correspondence for these groups
A simple combinatorial proof of a generalization of a result of Polo Author: F. Caselli Representation Theory 8 (2004), 479-486
No full textWe provide a simple combinatorial proof of, and generalize, a theorem
of Polo which asserts that for any polynomial P with nonnegative integer
coefficients such that P(0)=1 there exist two permutations u and v in a
suitable symmetric group such that P is equal to the Kazhdan-Lusztig
polynomial Pu,v
Formulas for multi-parameter classes of Kazhdan-Lusztig polynomials for S(n)
No full textWe give explicit formulas for several classes of Kazhdan-Lusztig polynomials of the symmetric group which are related to others already considered in the literature. In particular, we generalize two theorems of Brenti and Simion [Explicit formulae for some classes of Kazhdan-Lusztig polynomials, J. Algebraic Combin. 11 (2000), 187-196], we prove an unpublished conjecture of Brenti, and we treat the case missing in Theorem 4.8 of [F. Caselli, Proof of two conjectures of Brenti and Simion on Kazhdan-Lusztig polynomials, J. Algebraic Combin. 18 (2003), 171-187]
Special matchings and permutations in Bruhat orders
No full textFor any permutation v, we show that the special matchings of v generate a Coxeter system. This gives new necessary conditions on an abstract poset to be isomorphic to a lower Bruhat interval of the symmetric group, and also answers in the affirmative, in the symmetric group case, a problem posed in [F. Brenti, F. Caselli, M. Marietti, Special matchings and Kazhdan-Lusztig polynomials, Adv. Math. 202 (2006) 555601]. (c) 2006 Elsevier Inc. All rights reserved
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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