Geometric applications of Chernoff-type estimates and a ZigZag approximation for balls

Artstein-Avidan, S.; Friedland, O.; Milman, V.

doi:10.1090/S0002-9939-05-08144-X

Geometric applications of Chernoff-type estimates and a ZigZag approximation for balls
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by S. Artstein-Avidan, O. Friedland and V. Milman PDF

Proc. Amer. Math. Soc. 134 (2006), 1735-1742 Request permission

Abstract:

In this paper we show that the euclidean ball of radius $1$ in $\mathbb {R}^n$ can be approximated up to $\varepsilon >0$, in the Hausdorff distance, by a set defined by $N = C(\varepsilon )n$ linear inequalities. We call this set a ZigZag set, and it is defined to be all points in space satisfying $50\%$ or more of the inequalities. The constant we get is $C(\varepsilon ) = C \ln (1/\varepsilon )/\varepsilon ^2$, where $C$ is some universal constant. This should be compared with the result of Barron and Cheang (2000), who obtained $N = Cn^2/\varepsilon ^2$. The main ingredient in our proof is the use of Chernoff’s inequality in a geometric context. After proving the theorem, we describe several other results which can be obtained using similar methods.

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