Now showing items 21-33 of 33

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      Generating partial Hadamard matrices as solutions to a Constraint Satisfaction Problem characterizing cliques  [Presentation]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Falcón Ganfornina, Raúl Manuel; Frau García, María Dolores; Gudiel Rodríguez, Félix; Güemes Alzaga, María Belén; Osuna Lucena, Amparo (2017-07)
      A procedure is described looking for partial Hadamard matrices, as cliques of a particular subgraph Gt of Ito’s Hadamard Graph Δ(4t) [9]. The key idea is translating the problem of extending a given clique Cm to a larger ...
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      Gröbner bases and cocyclic Hadamard matrices  [Presentation]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Falcón Ganfornina, Raúl Manuel; Frau García, María Dolores; Gudiel Rodríguez, Félix (2017-07)
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      Gröbner bases and cocyclic Hadamard matrices  [Article]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Falcón Ganfornina, Raúl Manuel; Frau García, María Dolores; Gudiel Rodríguez, Félix (Elsevier, 2018)
      Hadamard ideals were introduced in 2006 as a set of nonlin-ear polynomial equations whose zeros are uniquely related toHadamard matrices with one or two circulant cores of a given or-der. Based on this idea, the cocyclic ...
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      Homological models for semidirect products of finitely generated Abelian groups  [Article]

      Álvarez Solano, Víctor; Frau García, María Dolores; Real Jurado, Pedro; Armario Sampalo, José Andrés (2012)
      Let G be a semidirect product of finitely generated Abelian groups. We provide a method for constructing an explicit contraction (special homotopy equivalence) from the reduced bar construction of the group ring of G, ...
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      Matrices cocíclicas de Hadamard sobre productos semidirectos  [Presentation]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Real Jurado, Pedro (Alberto Márquez, 2002)
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      On higher dimensional cocyclic Hadamard matrices  [Article]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Real Jurado, Pedro (2015)
      Provided that a cohomological model for G is known, we describe a method for constructing a basis for n-cocycles over G, from which the whole set of n-dimensional n-cocyclic matrices over G may be straightforwardly calculated. ...
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      On ZZt × ZZ2 2-cocyclic Hadamard matrices  [Article]

      Álvarez Solano, Víctor; Gudiel Rodríguez, Félix; Güemes Alzaga, María Belén (Wiley, 2015)
      A characterization of ZZt × ZZ22 -cocyclic Hadamard matrices is described, de- pending on the notions of distributions, ingredients and recipes. In particular, these notions lead to the establishment of some bounds on ...
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      (Pseudo)-cocyclic (structured) Hadamard matrices over (quasi)groups  [Presentation]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Falcón Ganfornina, Raúl Manuel; Frau García, María Dolores; Gudiel Rodríguez, Félix; Güemes Alzaga, María Belén; Kotsireas, Ilias (2017)
      Progressing on a survey of the state of the art of cocyclic constructions for Hadamard matrices, we will prove that the family of Goethals-Seidel Hadamard matrices is (pseudo)-cocyclic over a certain family of quasigroups. ...
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      Rooted Trees Searching for Cocyclic Hadamard Matrices over D4t  [Presentation]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Gudiel Rodríguez, Félix; Osuna Lucena, Amparo (Springer, 2009)
      A new reduction on the size of the search space for cocyclic Hadamard matrices over dihedral groups D4t is described, in terms of the so called central distribution. This new search space adopt the form of a forest ...
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      Searching for partial Hadamard matrices  [Presentation]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Gudiel Rodríguez, Félix; Güemes Alzaga, María Belén; Martín García, Elena; Osuna Lucena, Amparo (Universidade de Santiago de Compostela, Servicio de Publicaciones, 2010)
      Three algorithms looking for pretty large partial Hadamard ma- trices are described. Here “large” means that hopefully about a third of a Hadamard matrix (which is the best asymptotic result known so far, [8]) is achieved. ...
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      The homological reduction method for computing cocyclic Hadamard matrices  [Article]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Real Jurado, Pedro (2009)
      An alternate method for constructing (Hadamard) cocyclic matrices over a finite group GG is described. Provided that a homological model View the MathML sourceB̄(Z[G])ϕ:⇌HFhG for GG is known, the homological reduction ...
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      Transferring TTP-structures via contraction  [Article]

      Frau García, María Dolores; Real Jurado, Pedro; Armario Sampalo, José Andrés; Álvarez Solano, Víctor (2005)