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Ara es mostren els items 104-123 de 139

    • Quotient-polynomial graphs 

      Fiol Mora, Miquel Àngel (Elsevier, 2016-01-01)
      Article
      Accés restringit per política de l'editorial
      As a generalization of orbit-polynomial and distance-regular graphs, we introduce the concept of a quotient-polynomial graph. In these graphs every vertex uinduces the same regular partition around u, where all vertices ...

    • Reduction of connections for multibus organization 

      Lang, Tomás; Valero Cortés, Mateo; Fiol Mora, Miquel Àngel (1983-08)
      Article
      Accés obert
      The multibus interconnection network is an attractive solution for connecting processors and memory modules in a multiprocessor with shared memory. It provides a throughput which is intermediate between the single bus and ...

    • Sequence mixed graphs 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; López, Nacho (2016-12)
      Article
      Accés obert
      A mixed graph can be seen as a type of digraph containing some edges (or two opposite arcs). Here we introduce the concept of sequence mixed graphs, which is a generalization of both sequence graphs and literated line ...

    • Some applications of the proper and adjacency polynomials in the theory of graph spectra 

      Fiol Mora, Miquel Àngel (1997-09)
      Article
      Accés obert
      Given a vertex $u\inV$ of a graph $\Gamma=(V,E)$, the (local) proper polynomials constitute a sequence of orthogonal polynomials, constructed from the so-called $u$-local spectrum of $\Gamma$. These polynomials can be ...

    • Some families of orthogonal polynomials of a discrete variable and their applications to graphs and codes 

      Fiol Mora, Miquel Àngel; Garriga Valle, Ernest; Fàbrega Canudas, José; Cámara Vallejo, Marc (2000-08)
      Article
      Accés obert
      We 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 ...

    • Some results on the laplacian spectra of Token graphs 

      Dalfó Simó, Cristina; Duque, Frank; Fabila Monroy, Ruy; Fiol Mora, Miquel Àngel; Huemer, Clemens; Trujillo Negrete, Ana Laura; Zaragoza Martínez, Francisco (Springer, 2021)
      Text en actes de congrés
      Accés obert
      We study the Laplacian spectrum of token graphs, also called symmetric powers of graphs. The k-token graph Fk(G) of a graph G is the graph whose vertices are the k-subsets of vertices from G, two of which being adjacent ...

    • Some results on the structure of multipoles in the study of snarks 

      Fiol Mora, Miquel Àngel; Vilaltella Castanyer, Joan (2015-02-25)
      Article
      Accés obert
      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 ...

    • Some spectral and quasi-spectral characterizations of distance-regular graphs 

      Abiad, Aida; Van Dam, Edwin R; Fiol Mora, Miquel Àngel (2016-10-01)
      Article
      Accés obert
      In this paper we consider the concept of preintersection numbers of a graph. These numbers are determined by the spectrum of the adjacency matrix of the graph, and generalize the intersection numbers of a distance-regular ...

    • Spectra and eigenspaces from regular partitions of Cayley (di)graphs of permutation groups 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel (Elsevier, 2020-07-15)
      Article
      Accés obert
      In this paper, we present a method to obtain regular (or equitable) partitions of Cayley (di)graphs (that is, graphs, digraphs, or mixed graphs) of permutation groups on n letters. We prove that every partition of the ...

    • Spectra and eigenspaces of arbitrary lifts of graphs 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Pavlíková, Sona; Siran, Josef (2019)
      Article
      Accés obert
      We describe, in a very explicit way, a method for determining the spectra and bases of all the corresponding eigenspaces of arbitrary lifts of graphs (regular or not)

    • Spectra and eigenspaces of arbitrary lifts of graphs 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Pavlíková, Sona; Siran, Josef (2021-09)
      Article
      Accés obert
      We describe, in a very explicit way, a method for determining the spectra and bases of all the corresponding eigenspaces of arbitrary lifts of graphs (regular or not).

    • The (Delta,D) and (Delta,N) problems in double-step digraphs with unilateral diameter 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel (2013)
      Comunicació de congrés
      Accés obert
      We study the (D;D) and (D;N) problems for double-step digraphs considering the unilateral distance, which is the minimum between the distance in the digraph and the distance in its converse digraph, obtained by changing ...

    • The (Delta,D) and (Delta,N) problems in double-step digraphs with unilateral distance 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel (2014)
      Article
      Accés restringit per política de l'editorial
      We study the (delta;D) and (delta;N) problems for double-step digraphs considering the unilateral distance, which is the minimum between the distance in the digraph and the distance in its converse digraph, the latter ...

    • The alternating and adjacency polynomials, and their relation with the spectra and diameters of graphs 

      Fiol Mora, Miquel Àngel; Garriga Valle, Ernest (Elsevier Science Publishers B. V., 1998-10)
      Article
      Accés obert
      Let 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 design and control of dynamic memory networks 

      Fiol Mora, Miquel Àngel; Fàbrega Canudas, José; Yebra, José Luis A. (IEEE Press, 1988)
      Text en actes de congrés
      Accés obert
      A dynamic memory is a storage medium constituted by an array of cells and an interconnection network between them. It is characterized by the constant circulation of the stored data. The concern is to design the interconnection ...

    • The Diameter of undirected graphs associated to plane tessellations 

      Andrés Yebra, José Luis; Fiol Mora, Miquel Àngel; Morillo Bosch, M. Paz; Alegre de Miguel, Ignacio (1985)
      Article
      Accés obert
      Thi s paper studi es the di ameter of sorne fami I i es of undirected graphs that can be associated to plane tessel lations which fu1 ly represent them. More precisely, we concentrate upon maximizing the order of the ...

    • The dilating method to obtain dense cayley digraphs on finite abelian groups 

      Aguiló Gost, Francisco de Asis L.; Fiol Mora, Miquel Àngel; Pérez Mansilla, Sonia (2021-01-01)
      Article
      Accés obert
      A geometric method for obtaining an infinite family of Cayley digraphs of constant density on finite abelian groups is presented. The method works for any given degree d ≥ 2, and it is based on consecutive dilates of a ...

    • The generalized hierarchical product of graphs 

      Barrière Figueroa, Eulalia; Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Mitjana Riera, Margarida (2008-01)
      Article
      Accés obert
      A generalization of both the hierarchical product and the Cartesian product of graphs is introduced and some of its properties are studied. We call it the generalized hierarchical product. In fact, the obtained graphs ...

    • The geometry of t-cliques in k-walk-regular graphs 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Garriga Valle, Ernest (2008-09)
      Article
      Accés obert
      A 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 

      Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel; Garriga Valle, Ernest (Wiley InterScience, 2010-08)
      Article
      Accés obert
      A 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 ...