Now showing items 1-14 of 14

  • Almost every tree with m edges decomposes K2m,2m 

    Drmota, Michael; Lladó Sánchez, Ana M. (2014-01)
    Article
    Open Access
    We show that asymptotically almost surely a tree with m edges decomposes the complete bipartite graph K2m,2m, a result connected to a conjecture of Graham and Häggkvist. The result also implies that asymptotically almost ...
  • An interlacing approach for bounding the sum of Laplacian eigenvalues of graphs 

    Abiad, Aida; Fiol Mora, Miquel Àngel; Haemers, Willem H.; Perarnau Llobet, Guillem (2014)
    Conference report
    Open Access
    We apply eigenvalue interlacing techniques for obtaining lower and upper bounds for the sums of Laplacian eigenvalues of graphs, and characterize equality. This leads to generalizations of, and variations on theorems by ...
  • Approximate results for rainbow labelings 

    Lladó Sánchez, Ana M. (2015-04-14)
    External research report
    Open Access
  • Caracterizaciones combinatorias y algebraicas de grafos distancia-regulares 

    Fiol Mora, Miquel Àngel (Universitat Rovira i Virgili, 2014)
    Conference report
    Open Access
    Los grafos distancia-regulares aparecen a menudo en el estudio de es- tructuras matemáticas con un alto grado de simetría y/o regularidad. Un ejemplo bien conocido de tales grafos son los esqueletos ...
  • Connectivity: properties and structure 

    Balbuena Martínez, Maria Camino Teófila; Fàbrega Canudas, José; Fiol Mora, Miquel Àngel (CRC Press Taylor & Francis Group, 2013-12-05)
    Part of book or chapter of book
    Open Access
    Connectivity is one of the central concepts of graph theory, from both a theoret- ical and a practical point of view. Its theoretical implications are mainly based on the existence of nice max-min characterization results, ...
  • Cycle codes of graphs and MDS array codes 

    Serra Albó, Oriol; Zemor, Gilles (2009-07-30)
    Article
    Restricted access - publisher's policy
    We investigate how to colour edges of graph so that any two colours make up a spanning tree. This problem is equivalent to transforming the cycle code of a graph into a Maximum Distance Separable (MDS) array code. Adopting ...
  • Decomposing almost complete graphs by random trees 

    Lladó Sánchez, Ana M. (2015-04-14)
    External research report
    Open Access
  • Decomposing almost complete graphs by random trees 

    Lladó Sánchez, Ana M. (2014)
    Conference report
    Restricted access - publisher's policy
    An old conjecture of Ringel states that every tree with m edges decom- poses the complete graph K 2 m +1 . A more general version of the Ringel’s conjecture says that every tree with m edges decomposes K rm +1 for each r ...
  • Further topics in connectivity 

    Balbuena Martínez, Maria Camino Teófila; Fàbrega Canudas, José; Fiol Mora, Miquel Àngel (CRC Press Taylor & Francis Group, 2013-12-05)
    Part of book or chapter of book
    Open Access
    Continuing the study of connectivity, initiated in §4.1 of the Handbook, we survey here some (sufficient) conditions under which a graph or digraph has a given connectivity or edge-connectivity. First, we describe results ...
  • On the algebraic theory of pseudo-distance-regulariry around a set 

    Fiol Mora, Miquel Àngel; Garriga Valle, Ernest (Elsevier, 1999-09)
    Article
    Restricted access - publisher's policy
    Let C be a connected graph with vertex set V, adjacency matrix A, positive eigenvector and corresponding eigenvalue 0. A natural generalization of distance-regularity around a vertex subset C V , which makes sense ...
  • On the generalitzed arc routing problem 

    Fernández Aréizaga, Elena (2013)
    Conference report
    Open Access
  • Some results on the structure of multipoles in the study of snarks 

    Fiol Mora, Miquel Àngel; Vilaltella Castanyer, Joan (2015-02-25)
    Article
    Open Access
    Multipoles are the pieces we obtain by cutting some edges of a cubic graph in one or more points. As a result of the cut, a multipole M has vertices attached to a dangling edge with one free end, and isolated edges with ...
  • The Maximum degree of series-parallel graphs 

    Drmota, Michael; Giménez Llach, Omer; Noy Serrano, Marcos (2011-07)
    Article
    Restricted access - confidentiality agreement
    We prove that the maximum degree Δn of a random series-parallel graph with n vertices satisfies Δn/ log n → c in probability, and EΔn ∼ c log n for a computable constant c > 0. The same kind of result holds for 2-connected ...
  • Una fórmula explícita para obtener cuadrángulos generalizados y otros grafos pequeños de cintura 8 

    Abreu, M.; Balbuena Martínez, Maria Camino Teófila; Araujo Pardo, M. Gabriela; Labbate, D. (Universidad de Almería, 2011)
    Conference report
    Open Access
    Para cada potencia de primo q, se han constru do (q+1; 8)-jaulas como super cies cu adricas no degeneradas en 4-espacios proyectivos P(4; q). En primer lugar presentamos una construcci on de estos grafos de un modo ...