Equivalence operations for n-dimensional proper Hadamard matrices are defined. Their equivalence classes are investigated and bounds on the number of such equivalence classes are found to be associated with the number of equivalence classes of 2-dimensional Hadamard matrices. Properties of planes (2-dimensional sections) in an n-dimensional proper Hadamard matrix are investigated. It is shown t...

In this letter, a method to construct good binary and quaternary error correcting codes, called complex Hadamard codes, based on a complex Hadamard matrix is presented. The related properties of the codes are analyzed. In addition, through the operation in Z4 domain, a new simplex soft-decision decoding algorithm for the complex Hadamard codes is also proposed. key words: complex Hadamard matri...

William Thurston conjectured over twenty years ago that every compact hyperbolic 3manifold whose boundary is a possibly empty union of tori is finitely covered by a manifold which fibres over the circle. If true, it provides a significant amount of global information about the topology of such manifolds. The first non-trivial examples supporting the conjecture were obtained by Gabai [Ga1] (1986...

In this paper we study a one-dimensional quantum random walk with the Hadamard transformation which is often called the Hadamard walk. We construct the Hadamard walk using a transition matrix on probability amplitude and give some results on symmetricity of probability distributions for the Hadamard walk.

In 1867, Syvlester noted that the Kronecker product of two Hadamard matrices is an Hadamard matrix. This gave a way to obtain an Hadamard matrix of exponent four from two of exponent two. Early last decade, Agayan and Sarukhanyan found a way to combine two Hadamard matrices of exponent two to obtain one of exponent three, and just last year Craigen, Seberry and Zhang discovered how to combine f...

There is a well-known correspondence between symmetric 2-(4ju— 1,2/z — 1,/z — 1) designs and Hadamard matrices of order 4^. It is not so well known that there is a natural correspondence between Hadamard matrices of order 2\x and affine l-(4ju, 2^, 2(i) designs whose duals are also affine. Such a design is denoted by H^fi) in this paper. Under this natural correspondence, two H^fi) designs are ...

Hadamard matrices with a subjacent algebraic structure have been deeply studied as well as the links with other topics in algebraic combinatorics [1]. An important and pioneering paper about this subject is [5], where it is introduced the concept of Hadamard group. In addition, we find beautiful equivalences between Hadamard groups, 2-cocyclic matrices and relative difference sets [4], [7]. Fro...

In this paper all cocyclic Hadamard matrices of order less than 40 are classified. That is, all such Hadamard matrices are explicitly constructed, up to Hadamard equivalence. This represents a significant extension and completion of work by de Launey and Ito. The theory of cocyclic development is discussed, and an algorithm for determining whether a given Hadamard matrix is cocyclic is describe...

It is well-known that a Sylvester Hadamard matrix can be described by means of a cocycle. In this paper it is shown that the additional internal structure in a Sylvester Hadamard matrix, provided by the cocycle, is su cient to guarantee some kind of reduction in the computational complexity of calculating its permanent using Ryser's formula. A Hadamard matrix H of order n is an n× n matrix with...

in this paper we establish several polynomials similar to bernstein's polynomials and several refinements of  hermite-hadamard inequality for convex functions.