Butson full propelinear codes

Abstract

AbstractIn this paper we study Butson Hadamard matrices, and codes over finite rings coming from these matrices in logarithmic form, called BH-codes. We introduce a new morphism of Butson Hadamard matrices through a generalized Gray map on the matrices in logarithmic form, which is comparable to the morphism given in a recent note of Ó Catháin and Swartz. That is, we show how, if given a Butson Hadamard matrix over the $$k{\mathrm{th}}$$ k th roots of unity, we can construct a larger Butson matrix over the $$\ell \mathrm{th}$$ ℓ th roots of unity for any $$\ell $$ ℓ dividing k, provided that any prime p dividing k also divides $$\ell $$ ℓ . We prove that a $${\mathbb {Z}}_{p^s}$$ Z p s -additive code with p a prime number is isomorphic as a group to a BH-code over $${\mathbb {Z}}_{p^s}$$ Z p s and the image of this BH-code under the Gray map is a BH-code over $${\mathbb {Z}}_p$$ Z p (binary Hadamard code for $$p=2$$ p = 2 ). Further, we investigate the inherent propelinear structure of these codes (and their images) when the Butson matrix is cocyclic. Some structural properties of these codes are studied and examples are provided.