High Dimensional Random Sections of Isotropic Convex Bodies

نویسندگان

  • DAVID ALONSO-GUTIÉRREZ
  • GRIGORIS PAOURIS
چکیده

We study two properties of random high dimensional sections of convex bodies. In the first part of the paper we estimate the central section function |K ∩F⊥| n−k for random F ∈ Gn,k and K ⊂ R n a centrally symmetric isotropic convex body. This partially answers a question raised by V. Milman and A. Pajor (see [MP], p.88). In the second part we show that every symmetric convex body has random high dimensional sections F ∈ Gn,k with outer volume ratio bounded by ovr(K ∩ F ) ≤ C n n− k log „ 1 + n n− k «

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Asymptotics of Cross Sections for Convex Bodies

For normed isotropic convex bodies in R n we investigate the behaviour of the (n ? 1)-dimensional volume of intersections with hyperplanes orthogonal to a xed direction, considered as a function of the distance of the hyperplane to the origin. It is a conjecture that for arbitrary normed isotropic convex bodies and random directions this function { with high probability { is close to a Gaussian...

متن کامل

On Volume Distribution in 2-convex Bodies

We consider convex sets whose modulus of convexity is uniformly quadratic. First, we observe several interesting relations between different positions of such “2-convex” bodies; in particular, the isotropic position is a finite volume-ratio position for these bodies. Second, we prove that high dimensional 2-convex bodies posses one-dimensional marginals that are approximately Gaussian. Third, w...

متن کامل

On the existence of supergaussian directions on convex bodies

We study the question whether every centered convex body K of volume 1 in R has “supergaussian directions”, which means θ ∈ Sn−1 such that ̨̨̨̨ x ∈ K : |〈x, θ〉| > t Z K |〈x, θ〉|dx ff ̨̨̨̨ > e 2 , for all 1 6 t 6 √ n, where c > 0 is an absolute constant. We verify that a “random” direction is indeed supergaussian for isotropic convex bodies that satisfy the hyperplane conjecture. On the other hand, we ...

متن کامل

Random Aspects of High-dimensional Convex Bodies

In this paper we study geometry of compact, not necessarily centrally symmetric, convex bodies in R. Over the years, local theory of Banach spaces developed many sophisticated methods to study centrally symmetric convex bodies; and already some time ago it became clear that many results, if valid for arbitrary convex bodies, may be of interest in other areas of mathematics. In recent years many...

متن کامل

Random walks and an O*(n5) volume algorithm for convex bodies

Abstract Given a high dimensional convex body K ⊆ IR by a separation oracle, we can approximate its volume with relative error ε, using O∗(n5) oracle calls. Our algorithm also brings the body into isotropic position. As all previous randomized volume algorithms, we use “rounding” followed by a multiphase Monte-Carlo (product estimator) technique. Both parts rely on sampling (generating random p...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2009