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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. POMI, 2018 Volume 469, Pages 32–63 (Mi znsl6605)

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


 English version:
Journal of Mathematical Sciences (New York), 2019, 242:4, 487–508

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