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Chebyshevskii Sbornik, 2019, Volume 20, Issue 2, Pages 22–38
DOI: https://doi.org/10.22405/2226-8383-2018-20-2-22-38
(Mi cheb750)
 

About the method of estimating critical determinants within the question of the estimation of the constant of simultaneous diophantine approximations

Yu. A. Basalov

Tula State Pedagogical University of Leo Tolstoy (Tula)
References:
Abstract: This paper is devoted to the estimation of the constant of sumultaneous Diophantine approximations for $ n $ real numbers. The approach developed by H. Davenport and J. W. S. Cassels. H. Davenport discovered the connection between the value of the critical determinant of a star body and the estimation of some forms. In the particular case, this allows calculating the critical determinant of the $ (n + 1) $-dimensional star body of Davenport
$$ \mathbb {F}_{n}: | x_0 | \max \limits_{1 \leq i \leq n} | x_i |^n < 1, $$
get the value of the constant of joint Diophantine approximations. However, the calculation of critical determinants for bodies of this type is a difficult task. Therefore, J. W. S. Cassels moved from directly calculating the critical determinant, to estimating its value. For this, he used the estimate of the largest value of $ V_{n, s} $ – the volume of a parallelepiped centered at the origin of coordinates located inside the $ (n + 1) $-dimensional star body
$$ \mathbb {F}_{n, s}: f_{n, s} = \frac 1 {2^s} \prod \limits_{i = 1}^{s} | x_i^2 + x_{s + i}^2 | \prod \limits_{i = 2s + 1}^{n} | x_i | < 1. $$

These results reduce the problem of estimating the constant of joint Diophantine approximations to an estimate of the volume of the largest parallelepiped $ V_{n, s} $. Earlier, estimates for $ V_{n, s} $ were obtained in the works of J. W. S. Cassels, T. Cusick, S. Krass. This paper is devoted to methods of forming hypotheses about the values of $ V_{n, s} $ based on the results of numerical experiments. The article outlines the approach to obtaining parallelepipeds contained within a star body and possessing the largest volume. This approach combines the use of both numerical and analytical methods.
Keywords: best joint Diophantine approximations, geometry of numbers, star bodies, critical determinants.
Funding agency Grant number
Russian Foundation for Basic Research 19-41-710004_р_а
The study was supported by RFBR (grant 19-41-710004_р_а).
Received: 23.05.2019
Accepted: 12.07.2019
Document Type: Article
UDC: 511.9
Language: Russian
Citation: Yu. A. Basalov, “About the method of estimating critical determinants within the question of the estimation of the constant of simultaneous diophantine approximations”, Chebyshevskii Sb., 20:2 (2019), 22–38
Citation in format AMSBIB
\Bibitem{Bas19}
\by Yu.~A.~Basalov
\paper About the method of estimating critical determinants within the question of the estimation of the constant of simultaneous diophantine approximations
\jour Chebyshevskii Sb.
\yr 2019
\vol 20
\issue 2
\pages 22--38
\mathnet{http://mi.mathnet.ru/cheb750}
\crossref{https://doi.org/10.22405/2226-8383-2018-20-2-22-38}
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    References:17
     
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