Exploració per autor "Garriga Valle, Ernest"
Ara es mostren els items 15-31 de 31
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Moments in graphs
(2013)
Article
Accés obertLet G be a connected graph with vertex set V and a weight function that assigns a nonnegative number to each of its vertices. Then, the -moment of G at vertex u is de ned to be M G(u) = P v2V (v) dist(u; v), where ... -
Number of walks and degree powers in a graph
(2006-04)
Article
Accés obertThis letter deals with the relationship between the total number of k-walks in a graph, and the sum of the k-th powers of its vertex degrees. In particular, it is shown that the sum of all k-walks is upper bounded by the ... -
On Almost Distance-Regular Graphs
(2010-03-12)
Report de recerca
Accés obert -
On almost distance-regular graphs
(2010)
Article
Accés restringit per política de l'editorialDistance-regular graphs are a key concept in Algebraic Combinatorics and have given rise to several generalizations, such as association schemes. Motivated by spectral and other algebraic characterizations of distance-regular ... -
On k-Walk-Regular Graphs
(2008-08)
Article
Accés obertConsidering a connected graph $G$ with diameter $D$, we say that it is \emph{$k$-walk-regular}, for a given integer $k$ $(0\leq k \leq D)$, if the number of walks of length $\ell$ between vertices $u$ and $v$ only depends ... -
On outindependent subgraphs of strongly regular graphs
(Taylor & Francis, 2006)
Article
Accés obertAn outindependent subgraph of a graph G, with respect to an independent vertex subset C¿¿V, is the subgraph GC induced by the vertices in V\¿C. We study the case when G is strongly regular, where the results of de Caen ... -
On t-cliques in k-walk-regular graphs
(2009-08)
Article
Accés restringit per política de l'editorialA graph is walk-regular if the number of cycles of length rooted at a given vertex is a constant through all the vertices. For a walk-regular graph G with d+1 different eigenvalues and spectrally maximum diameter D = ... -
On t-cliques in k-walk-regular graphs
(Université de Bourdeaux, 2009)
Text en actes de congrés
Accés obert -
On the algebraic theory of pseudo-distance-regulariry around a set
(Elsevier, 1999-09)
Article
Accés restringit per política de l'editorialLet 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 local spectra of the subconstituents of a vertex set and completely pseudo-regular codes
(2014-10-30)
Article
Accés restringit per política de l'editorialIn this paper we study the relation between the local spectrum of a vertex set C and the local spectra of its subconstituents. In particular, it is shown that, when C is a completely regular code, such spectra are uniquely ... -
Problemes de Càlcul II
(Universitat Politècnica de Catalunya, 2000)
Apunts
Accés obert -
Some families of orthogonal polynomials of a discrete variable and their applications to graphs and codes
(2000-08)
Article
Accés obertWe present some related families of orthogonal polynomials of a discrete variable and survey some of their applications in the study of (distance-regular) graphs and (completely regular) codes. One of the main peculiarities ... -
The alternating and adjacency polynomials, and their relation with the spectra and diameters of graphs
(Elsevier Science Publishers B. V., 1998-10)
Article
Accés obertLet Γ be a graph on n vertices, adjacency matrix A, and distinct eigenvalues λ > λ_1 > λ_2 > · · · > λ_d. For every k = 0,1, . . . ,d −1, the k-alternating polynomial P_k is defined to be the polynomial of degree k and norm | -
The geometry of t-cliques in k-walk-regular graphs
(2008-09)
Article
Accés obertA graph is walk-regular if the number of cycles of length $\ell$ rooted at a given vertex is a constant through all the vertices. For a walk-regular graph $G$ with $d+1$ different eigenvalues and spectrally maximum ... -
The geometry of t-spreads in k-walk-regular graphs
(Wiley InterScience, 2010-08)
Article
Accés obertA graph is walk-regular if the number of closed walks of length rooted at a given vertex is a constant through all the vertices for all . For a walk-regular graph G with d+1 different eigenvalues and spectrally maximum ... -
When almost distance regularity attains distance regularity
(2010)
Text en actes de congrés
Accés restringit per política de l'editorial -
When almost distance-regularity attains distance-regularity
(2010)
Text en actes de congrés
Accés obertGenerally speaking, `almost distance-regular graphs' are graphs which share some, but not necessarily all, regularity properties that characterize distance-regular graphs. In this paper we rst propose four basic di erent ...
