Some notes on the $k$-normal elements and $k$-normal polynomials over finite fields

Abstract

Recently, the $k$-normal element over finite fields is defined and characterized by Huczynska et al.. In this paper, the characterization of $k$-normal elements, by using to give a generalization of Schwartz's theorem, which allows us to check if an element is a normal element, is obtained. In what follows, in respect of the problem of existence of a primitive 1-normal element in ${\mathbb{F}}_{q^n}$ over ${\mathbb{F}}_q$, for all $q$ and $n$, had been stated by Huczynska et al., it is shown that, in general, this problem is not satisfied. Finally, a recursive method for constructing $1$-normal polynomials of higher degree from a given $1$-normal polynomial over ${\mathbb{F}}_{2^m}$ is given.