The karyon algorithm for decomposition into multidimensional continued fractions
V. G. Zhuravlevab a Steklov Mathematical Institute of Russian Academy of Sciences, Moscow, Russia
b Vladimir State University, Vladimir, Russia
Abstract:
In this paper we propose a universal karyon algorithm, applicable to any set of real numbers
$\alpha=(\alpha_1,\dots,\alpha_d)$, which is a modification of the simplex-karyon algorithm. The main difference is an infinite sequence $\mathbf T=\mathbf T_0,\mathbf T_1,\dots,\mathbf T_n,\dots$ of
$d$-dimensional parallelohedra
$\mathbf T_n$ instead of the simplex sequence. Each parallelohedron
$\mathbf T_n$ is obtained from the previous
$\mathbf T_{n-1}$ by means of the differentiation
$\mathbf T_n=\mathbf T^{\sigma_n}_{n-1}$. Parallelohedra
$\mathbf T_n$ represent itself karyons of certain induced toric tilings. A certain algorithm (
$\varrho$-strategy) of the choice of infinite sequences $\sigma=\{\sigma_1,\sigma_2,\dots,\sigma_n,\dots\}$ of derivations
$\sigma_n$ is specified. This algorithm provides the convergence
$\varrho(\mathbf T_n)\to0$ if
$n\to+\infty$, where
$\varrho(\mathbf T_n)$ denotes the radius of the parallelohedron
$\mathbf T_n$ in the metric
$\varrho$ chosen as an objective function. It is proved that the parallelohedra
$\mathbf T_n$ have the minimum property, i.e. the karyon approximation algorithm is the best with respect to karyon
$\mathbf T_n$-norms. Also we get an estimate for the approximation rate of real numbers
$\alpha=(\alpha_1,\dots,\alpha_d)$ by multidimensional continued fractions.
Key words and phrases:
multidimensional continued fractions, the best approximations, simplex-karyon algorithm.
UDC:
511.3
Received: 09.02.2018