Quaternary Preparata codes are quasi-perfect covering codes in the Hamming metric
The quaternary Preparata codes of Hammons, Kumar, Calderbank, Sloane and Sol\'e are $\mathbb{Z}_4$-linear codes of length $2^m$ with $4^{2^m-m-1}$ codewords. They are usually studied through their binary Gray images, that is, in the Lee metric. We consider them instead as codes over a 4-letter alphabet with the Hamming...