We prove that, for any unit $ϵ$ in a real number field $K$ of degree $n+1$, there exits only a finite number of n-tuples in $K^n$ which have a purely periodic expansion by the Jacobi-Perron algorithm. This generalizes the case of continued fractions for $n=1$. For $n=2$ we give an explicit algorithm to compute all these pairs.

The technique of singularization was developped by C. Kraaikamp during the nineties, in connection with his work on dynamical systems related to continued fraction algorithms and their diophantine approximation properties. We generalize this technique from one into two dimensions. We apply the method to the the two dimensional Brun’s algorithm. We discuss, how this technique, and related ones, can be used to transfer certain metrical and diophantine properties from one algorithm to the others. In...

Let [0;a₁(x),a₂(x),…] be the regular continued fraction expansion of an irrational x ∈ [0,1]. We prove mainly that, for α > 0, β ≥ 0 and for almost all x ∈ [0,1], $li{m}_{n\to \infty }(aⁿ₁\left(x\right)+\dots +aⁿₙ\left(x\right))/nlogn=\alpha /log2$ if α < 1 and β ≥ 0, $li{m}_{n\to \infty }(aⁿ₁\left(x\right)+\dots +aⁿₙ\left(x\right))/nlogn=1/log2$ if α = 1 and β < 1, and, if α > 1 or α = 1 and β >1, $lim in{f}_{n\to \infty }(aⁿ₁\left(x\right)+\dots +aⁿₙ\left(x\right))/nlogn=1/log2$, $lim su{p}_{n\to \infty }(aⁿ₁\left(x\right)+\dots +aⁿₙ\left(x\right))/nlogn=\infty$, where $a{ⁿ}_i\left(x\right)=a_i\left(x\right)$ if $a_i\left(x\right)\le n^{\alpha }lo{g}^{\beta }n$ and $a{ⁿ}_i\left(x\right)=0$ otherwise, for all i ∈ 1,…,n.