| Title:
             | 
Estimating the critical determinants of a class of three-dimensional star bodies (English) | 
| Author:
             | 
Nowak, Werner Georg | 
| Language:
             | 
English | 
| Journal:
             | 
Communications in Mathematics | 
| ISSN:
             | 
1804-1388 | 
| Volume:
             | 
25 | 
| Issue:
             | 
2 | 
| Year:
             | 
2017 | 
| Pages:
             | 
149-157 | 
| Summary lang:
             | 
English | 
| . | 
| Category:
             | 
math | 
| . | 
| Summary:
             | 
In the problem of (simultaneous) Diophantine approximation in~$\mathbb{R}^3$ (in the spirit of Hurwitz's theorem), lower bounds for the critical determinant of the special three-dimensional body $$ K_2:\quad (y^2+z^2)(x^2+y^2+z^2)\le 1 $$ play an important role; see [1], [6]. This article deals with estimates from below for the critical determinant $\Delta (K_c)$ of more general star bodies $$ K_c:\quad (y^2+z^2)^{c/2}(x^2+y^2+z^2)\le 1, $$ where $c$ is any positive constant. These are obtained by inscribing into $K_c$ either a double cone, or an ellipsoid, or a double paraboloid, depending on the size of $c$. (English) | 
| Keyword:
             | 
Geometry of numbers; critical determinant; simultaneous Diophantine approximation | 
| MSC:
             | 
11H16 | 
| MSC:
             | 
11J13 | 
| idZBL:
             | 
Zbl 06888205 | 
| idMR:
             | 
MR3745434 | 
| . | 
| Date available:
             | 
2018-02-05T14:42:41Z | 
| Last updated:
             | 
2020-01-05 | 
| Stable URL:
             | 
http://hdl.handle.net/10338.dmlcz/147063 | 
| . | 
| Reference:
             | 
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| Reference:
             | 
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| Reference:
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| Reference:
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| Reference:
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| Reference:
             | 
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| Reference:
             | 
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| Reference:
             | 
[8] Nowak, W.G.: Lower bounds for simultaneous Diophantine approximation constants.Comm. Math., 22, 1, 2014, 71-76,  Zbl 1368.11063, MR 3233728 | 
| Reference:
             | 
[9] Nowak, W.G.: Simultaneous Diophantine approximation: Searching for analogues of Hurwitz's theorem.T.M. Rassias and P.M. Pardalos (eds.), Essays in mathematics and its applications, 2016, 181-197, Springer, Switzerland,  MR 3526920 | 
| Reference:
             | 
[10] Nowak, W.G.: On the critical determinants of certain star bodies.Comm. Math., 25, 1, 2017, 5-11,  MR 3667072, 10.1515/cm-2017-0002 | 
| Reference:
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| . |