Sums of two units in number fields

Magdaléna Tinková, Robin Visser, Pavlo Yatsyna

Let $K$ be a number field with ring of integers ${\mathcal{O}}_K$. Let ${\mathcal{N}}_K$ be the set of positive integers $n$ such that there exist units $\varepsilon, δ\in \mathcal{O}…