During his work devoted to Coxeter's friezes, M. Cuntz initiated the study of the notion of $\lambda$-quiddity and raised the problem of the study of this over some subsets of $\mathbb{ C}$. The objective of this text is to bring some new elements of response in the case of some cyclic subgroups of ($\mathbb{ C},+$) generated by an algebraic number. In particular, we will study the cases of subgroups generated by $a+b\sqrt{ k}$.
Categories: math.CO