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Volume thresholds for Gaussian and spherical random polytopes and their duals

Peter Pivovarov (2007)

Studia Mathematica

Let g be a Gaussian random vector in ℝⁿ. Let N = N(n) be a positive integer and let K N be the convex hull of N independent copies of g. Fix R > 0 and consider the ratio of volumes V N : = v o l ( K N R B ) / v o l ( R B ) . For a large range of R = R(n), we establish a sharp threshold for N, above which V N 1 as n → ∞, and below which V N 0 as n → ∞. We also consider the case when K N is generated by independent random vectors distributed uniformly on the Euclidean sphere. In this case, similar threshold results are proved for both R ∈ (0,1) and...

Volumetric invariants and operators on random families of Banach spaces

Piotr Mankiewicz, Nicole Tomczak-Jaegermann (2003)

Studia Mathematica

The geometry of random projections of centrally symmetric convex bodies in N is studied. It is shown that if for such a body K the Euclidean ball B N is the ellipsoid of minimal volume containing it and a random n-dimensional projection B = P H ( K ) is “far” from P H ( B N ) then the (random) body B is as “rigid” as its “distance” to P H ( B N ) permits. The result holds for the full range of dimensions 1 ≤ n ≤ λN, for arbitrary λ ∈ (0,1).

Weak and strong moments of random vectors

Rafał Latała (2011)

Banach Center Publications

We discuss a conjecture about comparability of weak and strong moments of log-concave random vectors and show the conjectured inequality for unconditional vectors in normed spaces with a bounded cotype constant.

Weak Distances between Random Subproportional Quotients of m

Piotr Mankiewicz (2012)

Bulletin of the Polish Academy of Sciences. Mathematics

Lower estimates for weak distances between finite-dimensional Banach spaces of the same dimension are investigated. It is proved that the weak distance between a random pair of n-dimensional quotients of n ² is greater than or equal to c√(n/log³n).

Zonoids with an equatorial characterization

Rafik Aramyan (2016)

Applications of Mathematics

It is known that a local equatorial characterization of zonoids does not exist. The question arises: Is there a subclass of zonoids admitting a local equatorial characterization. In this article a sufficient condition is found for a centrally symmetric convex body to be a zonoid. The condition has a local equatorial description. Using the condition one can define a subclass of zonoids admitting a local equatorial characterization. It is also proved that a convex body whose boundary is an ellipsoid...

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