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Browsing by Author "Armario Sampalo, José Andrés"
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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, ...

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 ...

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 ...

ACS Searching for D4tHadamard 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 ...

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 2cocycles on semidirect product offinite abelian groups is constructed, in light ofthe theory over cocyclic matrices developed by Horadam and de Launey in ...

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 ...

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, DGAalgebra) and X be a relatively free resolution of Λ over A. The standard bar resolution of Λ over A, denoted by B(A), provides ...

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 ...

Determinants of (–1,1)matrices of the skewsymmetric 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 skewsymmetric 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 ...

Embedding cocylic Doptimal 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 ...

Error correcting codes from quasiHadamard 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 ...

Estructuras multiplicativas y homología de fibrados [PhD Thesis]
Armario Sampalo, José Andrés (1999)Como es bien conocido, los principales mecanismos algebraicos para obtener información homológica de los espacios fibrados son las sucesiones espectrales de Serre y de EilenbergMoore. Dentro del contexto de la Topología ...

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, ...

Generalized binary arrays from quasiorthogonal cocycles [Article]
Armario Sampalo, José Andrés; Flannery, D. L. (Springer, 2019)Generalized perfect binary arrays (GPBAs) were used by Jedwab to construct perfect binary arrays. A nontrivial GPBA can exist only if its energy is 2 or a multiple of 4. This paper introduces generalized optimal binary ...

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)) ...

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 (201707)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 ...

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 (201707) 
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 nonlinear polynomial equations whose zeros are uniquely related toHadamard matrices with one or two circulant cores of a given order. Based on this idea, the cocyclic ...

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, ...

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)