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On Circulant Best Matrices And Their Applications, S. Georgiou, C. Koukouvinos, Jennifer Seberry
On Circulant Best Matrices And Their Applications, S. Georgiou, C. Koukouvinos, Jennifer Seberry
Professor Jennifer Seberry
Call four type 1(1,-1) matrices, x1,x2,x3,x4; of the same group of order m (odd) with the properties (i) (Xi-I)T = -(Xi-I), i=1,2,3, (ii)XT4 = X4 and the diagonal elements are positive, (iii) XiXj = XjXi and (iv) X1XT1 + X2XT2+X3XT3 +X4XT4 = 4mIm, best matrices. We use a computer to give, for the first time, all inequivalent best matrices of odd order m ≤31. Inequivalent best matrices of order m, m odd, can be used to find inequivalent skew-Hadamard matrices of order 4m. We use best matrices of order 1/4(s2+3) to construct new orthogonal designs, including new OD(2s2+6;1,1,2,2,s2,s2).
Orthogonal Designs From Negacyclic Matrices, K. Finlayson, Jennifer Seberry
Orthogonal Designs From Negacyclic Matrices, K. Finlayson, Jennifer Seberry
Professor Jennifer Seberry
We study the use of negacyclic matrices to form orthogonal designs and hence Hadamard matrices. We give results for all possible tuple for order 12, all but 3 for order 20 and all but 3 for order 28.
A New Method For Constructing T-Matrices, M. Xia, Tianbing Xia, Jennifer Seberry, G. Zuo
A New Method For Constructing T-Matrices, M. Xia, Tianbing Xia, Jennifer Seberry, G. Zuo
Professor Jennifer Seberry
For every prime power q = 3 (mod 8) we prove the existence of (q; x, 0, y, y)-partitions of GF(q) with q = x2 + 2y2 for some x, y, which are very useful for constructing SDS, T-matrices and Hadamard matrices. We discuss the transformations of (q; x, 0, y, y)-partitions and, by using the partitions, construct generalized cyclotomic classes which have properties similar to those of classical cyclotomic classes. Thus we provide a new construction for T-matrices of order q2.
An Algorithm To Find Formulae And Values Of Minors For Hadamard Matrices, C. Koukouvinos, M. Mitrouli, Jennifer Seberry
An Algorithm To Find Formulae And Values Of Minors For Hadamard Matrices, C. Koukouvinos, M. Mitrouli, Jennifer Seberry
Professor Jennifer Seberry
We give an algorithm to obtain formulae and values for minors of Hadamard matrices. One step in our algorithm allows the (n – j) x (n – j) minors of an Hadamard matrix to be given in terms of the minors of a 2j-1 x 2j-1 matrix. In particular we illustrate our algorithm by finding explicitly all the (n – 4) x (n – 4) minors of an Hadamard matrix.
An Algorithm To Find Formulae And Values Of Minors For Hadamard Matrices: Ii, C. Koukouvinos, E. Lappas, M. Mitrouli, Jennifer Seberry
An Algorithm To Find Formulae And Values Of Minors For Hadamard Matrices: Ii, C. Koukouvinos, E. Lappas, M. Mitrouli, Jennifer Seberry
Professor Jennifer Seberry
An algorithm computing the (n — j) x (n — j ) , j = 1, 2, ... minors of Hadamard matrices of order n is presented. Its implementation is analytically described step by step for several values of n and j. For j = 7 the values of minors are computed for the first time. A formulae estimating all the values of (n — j) x (n — j) minors is predicted.