1,721,077 research outputs found
Nonintersecting ryser hypergraphs
No full textA famous conjecture of Ryser states that every r-partite hypergraph has vertex cover number at most r 1 times the matching number. In recent years, hypergraphs meeting this conjectured bound, known as r-Ryser hypergraphs, have been studied extensively. It was proved by Haxell, Narins, and Szabó that all 3-Ryser hypergraphs with matching number v > 1 are essentially obtained by taking v disjoint copies of intersecting 3-Ryser hypergraphs. Abu-Khazneh showed that such a characterization is false for r = 4 by giving a computer generated example of a 4-Ryser hypergraph with v = 2 whose vertex set cannot be partitioned into two sets such that we have an intersecting 4-Ryser hypergraph on each of these parts. Here we construct first infinite families of r-Ryser hypergraphs, for any fixed matching number v > 1, that are truly nonintersecting in the sense that they do not contain two vertex disjoint intersecting r-Ryser subhypergraphs
STATO DEMOCRATICO E SOCIETA' MULTICULTURALE DALLA TUTELA DELLE MINORANZE AL RICONOSCIMENTO DELLE DIVERSITA' CULTURALI
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(d, σ) -Veronese variety and some applications
Full text linkLet K be the Galois field of order q^t , A = Aut(K) be the automorphism group of K and σ = (σ0, . . . , σd−1) in A^d , d ≥ 1. In this paper the following
generalization of the Veronese map is studied:
νd,σ : 〈v〉 ∈ PG(n − 1, K) −→ 〈v ^σ0 ⊗ v^ σ1 ⊗ · · · ⊗ v^ σd−1 〉 ∈ PG(n d − 1, K).
Its image will be called the (d, σ )-Veronese variety Vd,σ . We will show that Vd,σ is the Grassmann embedding of a normal rational
scroll and any d + 1 points of it are linearly independent. We give a characterization of d + 2
linearly dependent points of Vd,σ and for some choices of parameters, Vp,σ is the normal
rational curve; for p = 2, it can be the Segre’s arc of PG(3, q^t ); for p = 3 Vp,σ can be also a
|Vp,σ |-track of PG(5, q^t ). Finally, investigate the link between such points sets and a linear
code Cd,σ that can be associated to the variety, obtaining examples of MDS and almost MDS codes
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
The influence of pre-fermentative practices on the dominance of inoculated yeast starter under industrial condition
No full textVariations 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
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