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Ponencia
Error correcting codes from quasi-Hadamard matrices
(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 ...
Artículo
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
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
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
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
Equivalences of Zt×Z22-cocyclic Hadamard matrices
(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 × ...
Ponencia
Searching for partial Hadamard matrices
(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. ...
Artículo
Hadamard Matrices with Cocyclic Core
(MDPI, 2021)
Since Horadam and de Launey introduced the cocyclic framework on combinatorial designs in the 1990s, it has revealed itself as a powerful technique for looking for (cocyclic) Hadamard matrices. Ten years later, the series ...
Artículo
Pseudococyclic Partial Hadamard Matrices over Latin Rectangles
(MDPI [Commercial Publisher], 2021-01-06)
The classical design of cocyclic Hadamard matrices has recently been generalized by means of both the notions of the cocycle of Hadamard matrices over Latin rectangles and the pseudococycle of Hadamard matrices over ...
Ponencia
Rooted Trees Searching for Cocyclic Hadamard Matrices over D4t
(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 ...