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Mostrando ítems 1-10 de 19
Artículo
Self-Dual codes from (−1,1)-matrices of skew symmetric type
(Cornell University, 2013)
Previously, self-dual codes have been constructed from weighing matrices, and in particular from conference matrices (skew and symmetric). In this paper, codes constructed from matrices of skew symmetric type whose ...
Artículo
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
On an inequivalence criterion for cocyclic Hadamard matrices
(Springer, 2010)
Given two Hadamard matrices of the same order, it can be quite difficult to decide whether or not they are equivalent. There are some criteria to determine Hadamard inequivalence. Among them, one of the most commonly ...
Artículo
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
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
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
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
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)) ...
Artículo
On quasi-orthogonal cocycles
(Wiley, 2017)
We introduce the notion of quasi-orthogonal cocycle. This is motivated in part by the maximal determinant problem for square {±1}-matrices of size congruent to 2 modulo 4. Quasi-orthogonal cocycles are analogous to the ...
Artículo
Embedding cocylic D-optimal designs in cocylic Hadamard matrices
(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 ...