Ara es mostren els items 1-12 de 13

    • The group inverse of circulant matrices depending on four parameters 

      Carmona Mejías, Ángeles; Encinas Bachiller, Andrés Marcos; Jiménez Jiménez, María José; Mitjana Riera, Margarida (De Gruytr, 2021-10-27)
      Article
      Accés obert
      Explicit expressions for the coefficients of the group inverse of a circulant matrix depending on four complex parameters are analytically derived. The computation of the entries of the group inverse are now reduced to the ...
    • A combinatorial expression for the group inverse of symmetric M-matrices 

      Carmona Mejías, Ángeles; Encinas Bachiller, Andrés Marcos; Mitjana Riera, Margarida (De Gruytr, 2021-04-27)
      Article
      Accés obert
      By using combinatorial techniques, we obtain an extension of the matrix-tree theorem for general symmetric M-matrices with no restrictions, this means that we do not have to assume the diagonally domi nance hypothesis. We ...
    • Problema 168 

      Bendito Pérez, Enrique; Carmona Mejías, Ángeles; Encinas Bachiller, Andrés Marcos; Mitjana Riera, Margarida (Real Sociedad Matemática Española, 2010)
      Article
      Accés obert
    • Eigenvalues with respect to a weight for general boundary value problems on networks 

      Carmona Mejías, Ángeles; Encinas Bachiller, Andrés Marcos; Mitjana Riera, Margarida (Elsevier, 2021-04-01)
      Article
      Accés obert
      In this work we analyze self-adjoint boundary value problems on networks for Schrödinger operators, in which a part of the boundary with a Neumann condition is always considered. We first characterize when the energy is ...
    • Drazin inverse of singular adjacency matrices of directed weighted cycles 

      Encinas Bachiller, Andrés Marcos (2020-09-25)
      Article
      Accés obert
      We present a necessary and sufficient condition for the singularity of circulant matrices associated with directed weighted cycles. This condition is simple and independent of the order of matrices from a complexity point ...
    • Group inverse matrix of the normalized Laplacian on subdivision networks 

      Carmona Mejías, Ángeles; Mitjana Riera, Margarida; Monsó Burgués, Enrique P.J. (2020)
      Article
      Accés obert
      In this paper we consider a subdivision of a given network and we show how the group inverse matrix of the normalized laplacian of the subdivision network is related to the group inverse matrix of the normalized laplacian ...
    • The group inverse of some circulant matrices 

      Carmona Mejías, Ángeles; Encinas Bachiller, Andrés Marcos; Jiménez Jiménez, María José; Mitjana Riera, Margarida (Elsevier, 2020-11-12)
      Article
      Accés obert
      In a previous work the authors presented the necessary and sufficient conditions for the invertibility of some circulant matrices that depend on three real parameters and, moreover, we obtained a closed formula for their ...
    • Boundary value problems for second order linear difference equations: application to the computation of the inverse of generalized Jacobi matrices 

      Encinas Bachiller, Andrés Marcos; Jiménez Jiménez, María José (Springer, 2019-07-22)
      Article
      Accés obert
      We have named generalized Jacobi matrices to those that are practically tridiagonal, except for the two final entries and the two first entries of its first andits last row respectively. This class of matrices encompasses ...
    • Green functions on product networks 

      Arauz Lombardía, Cristina; Carmona Mejías, Ángeles; Encinas Bachiller, Andrés Marcos; Mitjana Riera, Margarida (2018-01-01)
      Article
      Accés obert
      We aim here at determining the Green function for general Schrödinger operators on product networks. The first step consists in expressing Schrödinger operators on a product network as sum of appropriate Schrödinger operators ...
    • Resistance distances in extended or contracted networks 

      Carmona Mejías, Ángeles; Encinas Bachiller, Andrés Marcos; Mitjana Riera, Margarida (Elsevier, 2019-09-01)
      Article
      Accés obert
      In this paper we introduce new effective resistances on a given network, associated with a positive value and two weights on the vertex set and investigate under which conditions they determine a distance. We prove that ...
    • Explicit inverse of nonsingular Jacobi matrices 

      Encinas Bachiller, Andrés Marcos; Jiménez Jiménez, María José (2019-06-30)
      Article
      Accés obert
      We present here the necessary and sufficient conditions for the invertibility of tridiagonal matrices, commonly named Jacobi matrices, and explicitly compute their inverse. The techniques we use are related with the solution ...
    • Triangular sequences, combinatorial recurrences and linear difference equations 

      Encinas Bachiller, Andrés Marcos; Jiménez Jiménez, María José (Elsevier, 2019-09-01)
      Article
      Accés obert
      In this work we introduce the triangular double sequences of arbitrary order given by linear recurrences, that generalize some well-known recurrences that appear in enumerative combinatorics. In particular, we focussed on ...