Abstract
Let \(n\in{\mathbb N}\) and let \(Q_n\) be the unit cube \([0,1]^n\). For a nondegenerate simplex \(S\subset{\mathbb R}^n\), by \(\sigma S\) denote the homothetic copy of \(S\) with center of homothety in the center of gravity of \(S\) and ratio of homothety \(\sigma.\) Put \(\xi(S)=\min \{\sigma\geq 1: Q_n\subset \sigma S\}.\) We call \(\xi(S)\) an absorption index of simplex \(S\). In the present paper, we give new estimates for the minimal absorption index of the simplex contained in \(Q_n\), i.\,e., for the number \(\xi_n=\min \{ \xi(S): , S\subset Q_n \}.\) In particular, this value and its analogues have applications in estimates for the norms of interpolation projectors. Previously the first author proved some general estimates of \(\xi_n\). Always \(n\leq\xi_n 2)\). There exists a constant \(c>0\) not depending on \(n\) such that, for any simplex \(S\subset Q_n\) of maximum volume, inequalities \(c\xi(S)\leq \xi_n\leq \xi(S)\) take place. It motivates the use of maximum volume simplices in upper estimates of \(\xi_n\). The set of vertices of such a simplex can be consructed with application of maximum \(0/1\)-determinant of order \(n\) or maximum \(-1/1\)-determinant of order \(n+1\). In the paper, we compute absorption indices of maximum volume simplices in \(Q_n\) constructed from known maximum \(-1/1\)-determinants via a special procedure. For some \(n\), this approach makes it possible to lower theoretical upper bounds of \(\xi_n\). Also we give best known upper estimates of \(\xi_n\) for \(n\leq 118\)
Highlights
by σS denote the homothetic copy of S with center
we give new estimates for the minimal absorption index of the simplex contained in Qn
Previously the first author proved some general estimates of ξn
Summary
Для невырожденного симплекса S ⊂ Rn через σS 0, такая что для любого симплекса S ⊂ Qn, имеющего максимальный объём, выполняются неравенства cξ(S) ≤ ξn ≤ ξ(S). Ю., "О минимальном коэффициенте поглощения для n-мерного симплекса", Моделирование и анализ информационных систем, 25:1 (2018), 140–150. Ю. О минимальном коэффициенте поглощения для n-мерного симплекса
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