Enviaments recents

  • A generalisation of Sylvester's problem to higher dimensions 

    Ball, Simeon Michael; Monserrat, Joaquim (2017-07-01)
    Article
    Accés obert
    In this article we consider $S$ to be a set of points in $d$-space with the property that any $d$ points of $S$ span a hyperplane and not all the points of $S$ are contained in a hyperplane. The aim of this article is to ...
  • A finite version of the Kakeya problem 

    Ball, Simeon Michael; Blokhuis, Aart; Domenzain, Diego (2016-06-02)
    Article
    Accés obert
    Let $L$ be a set of lines of an affine space over a field and let $S$ be a set of points with the property that every line of $L$ is incident with at least $N$ points of $S$. Let $D$ be the set of directions of the lines ...
  • On quotient digraphs and voltage digraphs 

    Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Miller, Mirka; Ryan, Joe (2017-10)
    Article
    Accés obert
    We study the relationship between two key concepts in the theory of digraphs, those of quotient digraphs and voltage digraphs. These techniques contract or expand a given digraph in order to study its characteristics,or ...
  • From expanded digraphs to voltage and line digraphs 

    Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Miller, Mirka; Ryan, Joe (2017-10)
    Article
    Accés obert
    In this note we present a general approach to construct large digraphs from small ones. These are called expanded digraphs, and, as particular cases, we show the close relationship between lifted digraphs of voltage digraphs ...
  • The spectra of subKautz and cyclic Kautz digraphs 

    Dalfó Simó, Cristina (Elsevier, 2017-10-15)
    Article
    Accés obert
    Kautz digraphs K(d,l) are a well-known family of dense digraphs, widely studied as a good model for interconnection networks. Closely related with these, the cyclic Kautz CK(d,l) and the subKautz sK(d,2) digraphs were ...
  • A new labeling construction from the -product 

    López Masip, Susana Clara; Muntaner Batle, Francesc Antoni; Prabu, M. (2017-08-01)
    Article
    Accés restringit per política de l'editorial
    The ¿h-product that is referred in the title was introduced in 2008 as a generalization of the Kronecker product of digraphs. Many relations among labelings have been obtained since then, always using as a second factor a ...
  • The number and degree distribution of spanning trees in the Tower of Hanoi graph 

    Zhang, Zhongzhi; Wu, Shunqi; Li, Mingyun; Comellas Padró, Francesc de Paula (2016-01-04)
    Article
    Accés restringit per política de l'editorial
    The number of spanning trees of a graph is an important invariant related to topological and dynamic properties of the graph, such as its reliability, communication aspects, synchronization, and so on. However, the practical ...
  • Iterated line digraphs are asymptotically dense 

    Dalfó Simó, Cristina (Elsevier, 2017)
    Article
    Accés obert
    We show that the line digraph technique, when iterated, provides dense digraphs, that is, with asymptotically large order for a given diameter (or with small diameter for a given order). This is a well- known result for ...
  • The normalized Laplacian spectrum of subdivisions of a graph 

    Xie, Pinchen; Zhang, Zhongzhi; Comellas Padró, Francesc de Paula (2016-08-05)
    Article
    Accés restringit per política de l'editorial
    Determining and analyzing the spectra of graphs is an important and exciting research topic in mathematics science and theoretical computer science. The eigenvalues of the normalized Laplacian of a graph provide information ...
  • On perfect and quasiperfect dominations in graphs 

    Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel; Cáceres, José; Puertas, M. Luz (2017-02-27)
    Article
    Accés obert
    A subset S ¿ V in a graph G = ( V , E ) is a k -quasiperfect dominating set (for k = 1) if every vertex not in S is adjacent to at least one and at most k vertices in S . The cardinality of a minimum k -quasiperfect ...

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