Orthogonal designs and symmetric Hadamard matrices
Our main result is the construction of symmetric Hadamard matrices of order q(1 + q) where q is a prime power congruent to 3 mod 8.
math.CO↗
arXiv subjects
Dragomir Ž. Djoković
Publications and source records attributed to Dragomir Ž. Djoković.
Hadamard matrices: skew of orders 276, 292 and symmetric 372
The smallest integer v>0 for which no skew-Hadamard matrix of order 4v is known is v=69. We show how to construct several such matrices. We also construct presumably the first example of a skew-Hadamard matrix of order 292, and the first examples of symmetric Hadamard matrices of order 372.
math.CO↗
A few new orders for D-optimal matrices
The first examples of D-optimal matrices of orders 222, 234, 258 and 278 are constructed.
math.CO↗
A heuristic algorithm for computing the Poincaré series of the invariants of binary forms
We propose a heuristic algorithm for fast computation of the Poincaré series $P_n(t)$ of the invariants of binary forms of degree $n$, viewed as rational functions. The algorithm is based on certain polynomial identities which remain to be proved rigorously. By using it, we have computed the $P_n(t)$ for $n\le30$.
math.AC↗