Buscar
Mostrando ítems 1-10 de 19
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
Algebra Structures on the Comparison of the Reduced Bar Construction and the Reduced W-Construction
(Taylor and Francis, 2009)
For a simplicial augmented algebra K, Eilenberg–Mac Lane constructed a chain map . They proved that g is a reduction (homology isomorphism) and conjectured that it is also the injection of a contraction (special homotopy ...
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
On Cocyclic Hadamard Matrices over Goethals-Seidel Loops
(MDPI, 2020)
About twenty-five years ago, Horadam and de Launey introduced the cocyclic development of designs, from which the notion of cocyclic Hadamard matrices developed over a group was readily derived. Much more recently, it ...
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
A Mixed Heuristic for Generating Cocyclic Hadamard Matrices
(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 ...
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
On D4t-Cocyclic Hadamard Matrices
(Wiley, 2016)
In this paper, we describe some necessary and sufficient conditions for a set of coboundaries to yield a cocyclic Hadamard matrix over the dihedral group D4t. Using this characterization, new classification results for ...
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
Determinants of (–1,1)-matrices of the skew-symmetric type: a cocyclic approach
(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 ...
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
On higher dimensional cocyclic Hadamard matrices
(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. ...
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
A System of Equations for Describing Cocyclic Hadamard Matrices
(Wiley, 2008)
Given a basis equation image for 2-cocycles equation image over a group G of order equation image, we describe a nonlinear system of 4t-1 equations and k indeterminates equation image over equation image, whose solutions ...
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
The homological reduction method for computing cocyclic Hadamard matrices
(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 ...
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
GA Based Robust Blind Digital Watermarking
(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, ...
Artículo
![Con acceso al texto completo Icon](/themes/idUS//images/acceso/opened_access.png)
Generating binary partial Hadamard matrices
(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)) ...