Let ε be an algebraic unit for which the rank of the group of units of the order ℤ[ε] is equal to 1. Assume that ε is not a complex root of unity. It is natural to wonder whether ε is a fundamental unit of this order. It turns out that the answer is in general yes, and that a fundamental unit of this order can be explicitly given (as an explicit polynomial in ε) in the rare cases when the answer is no. This paper is a self-contained exposition of the solution to this problem, solution which was...

Let $𝒪$ be the maximal order of the cubic field generated by a zero $\epsilon$ of $x^3+(\ell -1)x^2-\ell x-1$ for $\ell \in \mathbb{Z}$, $\ell \ge 3$. We prove that $\epsilon ,\epsilon -1$ is a fundamental pair of units for $𝒪$, if $[𝒪:\mathbb{Z}[\epsilon \left]\right]\le \ell /3.$