Now showing items 1-20 of 33

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      A computational algebraic geometry approach to analyze pseudo-random sequences based on Latin squares  [Article]

      Falcón Ganfornina, Raúl Manuel; Álvarez Solano, Víctor; Gudiel Rodríguez, Félix (Springer, 2019)
      Latin squares are used as scramblers on symmetric-key algorithms that generate pseudo-random sequences of the same length. The robustness and effectiveness of these algorithms are respectively based on the extremely large ...
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      A genetic algorithm for cocyclic hadamard matrices  [Chapter of Book]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Real Jurado, Pedro (2006)
      A genetic algorithm for finding cocyclic Hadamard matrices is described. Though we focus on the case of dihedral groups, the algorithm may be easily extended to cover any group. Some executions and examples are also included, ...
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      A Heuristic Procedure with Guided Reproduction for Constructing Cocyclic Hadamard Matrices  [Presentation]

      Álvarez Solano, Víctor; Frau García, María Dolores; Osuna Lucena, Amparo (Springer, 2009)
      A genetic algorithm for constructing cocyclic Hadamard matrices over a given group is described. The novelty of this algorithm is the guided heuristic procedure for reproduction, instead of the classical crossover and ...
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      A Mathematica Notebook for Computing the Homology of Iterated Products of Groups  [Chapter of Book]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Real Jurado, Pedro (2006)
      Let G be a group which admits the structure of an iterated product of central extensions and semidirect products of abelian groups G i (both finite and infinite). We describe a Mathematica 4.0 notebook for computing the ...
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      A Mixed Heuristic for Generating Cocyclic Hadamard Matrices  [Article]

      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 (Springer, 2018)
      A way of generating cocyclic Hadamard matrices is described, which combines a new heuristic, coming from a novel notion of fitness, and a peculiar local search, defined as a constraint satisfaction problem. Calculations ...
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      ACS Searching for D4t-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 (Springer, 2010)
      An Ant Colony System (ACS) looking for cocyclic Hadamard matrices over dihedral groups D4t is described. The underlying weighted graph consists of the rooted trees described in [1], whose vertices are certain subsets ...
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      An algorithm for computing cocyclic matrices developed over some semidirect products  [Chapter of Book]

      Armario Sampalo, José Andrés; Frau García, María Dolores; Real Jurado, Pedro; Álvarez Solano, Víctor (2001)
      An algorithm for calculating a set ofgenerators ofrepresentative 2-cocycles on semidirect product offinite abelian groups is constructed, in light ofthe theory over cocyclic matrices developed by Horadam and de Launey in ...
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      Calculating cocyclic hadamard matrices in Mathematica: exhaustive and heuristic searches  [Chapter of Book]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Real Jurado, Pedro (2006)
      We describe a notebook in Mathematica which, taking as input data a homological model for a finite group G of order |G| = 4t, performs an exhaustive search for constructing the whole set of cocyclic Hadamard matrices over ...
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      Cocyclic Hadamard matrices over Latin rectangles  [Presentation]

      Falcón Ganfornina, Raúl Manuel; Frau García, María Dolores; Güemes Alzaga, María Belén; Gudiel Rodríguez, Félix; Álvarez Solano, Víctor (2017)
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      Cocyclic Hadamard matrices over Latin rectangles  [Article]

      Álvarez Solano, Víctor; Falcón Ganfornina, Raúl Manuel; Frau García, María Dolores; Gudiel Rodríguez, Félix; Güemes Alzaga, María Belén (Elsevier, 2019)
      In the literature, the theory of cocyclic Hadamard matrices has always been developed over finite groups. This paper introduces the natural generalization of this theory to be developed over Latin rectangles. In this ...
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      Comparison maps for relatively free resolutions  [Chapter of Book]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Real Jurado, Pedro (2006)
      Let Λ be a commutative ring, A an augmented differential graded algebra over Λ (briefly, DGA-algebra) and X be a relatively free resolution of Λ over A. The standard bar resolution of Λ over A, denoted by B(A), provides ...
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      Complejos reducidos de resoluciones y perturbación homológica  [PhD Thesis]

      Álvarez Solano, Víctor (2001)
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      Computing “Small” 1–Homological Models for Commutative Differential Graded Algebras  [Presentation]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; González Díaz, Rocío; Jiménez Rodríguez, María José; Real Jurado, Pedro; Silva Gallardo, Beatriz (Springer, 2000)
      We use homological perturbation machinery specific for the algebra category [13] to give an algorithm for computing the differential structure of a small 1– homological model for commutative differential graded algebras ...
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      Desarrollo cocíclico de diseños y aplicaciones  [PhD Thesis]

      Frau García, María Dolores (2003)
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      Determinants of (–1,1)-matrices of the skew-symmetric type: a cocyclic approach  [Article]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Gudiel Rodríguez, Félix (Walter de Gruyter GmbH, 2015)
      An n by n skew-symmetric type (−1, 1)-matrix K = [ki,j ] has 1’s on the main diagonal and ±1’s elsewhere with ki,j = −kj,i. The largest possible determinant of such a matrix K is an interesting problem. The literature ...
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      Embedding cocylic D-optimal designs in cocylic Hadamard matrices  [Article]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Gudiel Rodríguez, Félix (International Linear Algebra Society, 2012)
      A method for embedding cocyclic submatrices with “large” determinants of orders 2t in certain cocyclic Hadamard matrices of orders 4t is described (t an odd integer). If these determinants attain the largest possible ...
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      Equivalences of Zt×Z22-cocyclic Hadamard matrices  [Article]

      Álvarez Solano, Víctor; Gudiel Rodríguez, Félix; Güemes Alzaga, María Belén; Horadam, K.J.; Rao, A. (Cornell University, 2015)
      One of the most promising structural approaches to resolving the Hadamard Conjecture uses the family of cocyclic matrices over Zt × Z2 2. Two types of equivalence relations for classifying cocyclic matrices over Zt × ...
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      Error correcting codes from quasi-Hadamard matrices  [Presentation]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Martín García, Elena; Osuna Lucena, Amparo (Springer, 2007)
      Levenshtein described in [5] a method for constructing error correcting codes which meet the Plotkin bounds, provided suitable Ha- damard matrices exist. Uncertainty about the existence of Hadamard matrices on all orders ...
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      GA Based Robust Blind Digital Watermarking  [Article]

      Álvarez Solano, Víctor; Armario Sampalo, José Andrés; Frau García, María Dolores; Gudiel Rodríguez, Félix; Güemes Alzaga, María Belén; Martín García, Elena; Osuna Lucena, Amparo (Elsevier, 2018)
      A genetic algorithm based robust blind digital watermarking scheme is presented. The experimental results show that our scheme keeps invisibility, security and robustness more likely than other proposals in the literature, ...
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      Generating binary partial Hadamard matrices  [Article]

      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 (Elsevier, 2019)
      This paper deals with partial binary Hadamard matrices. Although there is a fast simple way to generate about a half (which is the best asymptotic bound known so far, see de Launey (2000) and de Launey and Gordon (2001)) ...