Inequalities for random flats meeting a convex body

1985 ◽  
Vol 22 (03) ◽  
pp. 710-716 ◽  
Author(s):  
Rolf Schneider
Keyword(s):  
Convex Body ◽  
Euclidean Space ◽  
Finite Number ◽  
Random Point ◽  
Dimensional Euclidean Space ◽  
Random Direction ◽  
Higher Dimensional

We choose a uniform random point in a given convex bodyKinn-dimensional Euclidean space and through that point the secant ofKwith random direction chosen independently and isotropically. Given the volume ofK, the expectation of the length of the resulting random secant ofKwas conjectured by Enns and Ehlers [5] to be maximal ifKis a ball. We prove this, and we also treat higher-dimensional sections defined in an analogous way. Next, we consider a finite number of independent isotropic uniform random flats meetingK, and we prove that certain geometric probabilities connected with these again become maximal whenKis a ball.

Inequalities for random flats meeting a convex body

1985 ◽  
Vol 22 (3) ◽  
pp. 710-716 ◽  
Author(s):  
Rolf Schneider
Keyword(s):  
Convex Body ◽  
Euclidean Space ◽  
Finite Number ◽  
Random Point ◽  
Dimensional Euclidean Space ◽  
Random Direction ◽  
Higher Dimensional

We choose a uniform random point in a given convex body K in n-dimensional Euclidean space and through that point the secant of K with random direction chosen independently and isotropically. Given the volume of K, the expectation of the length of the resulting random secant of K was conjectured by Enns and Ehlers [5] to be maximal if K is a ball. We prove this, and we also treat higher-dimensional sections defined in an analogous way. Next, we consider a finite number of independent isotropic uniform random flats meeting K, and we prove that certain geometric probabilities connected with these again become maximal when K is a ball.

scholarly journals The mathematical foundations of anelasticity: existence of smooth global intermediate configurations

2021 ◽  
Vol 477 (2245) ◽  
pp. 20200462
Author(s):  
Christian Goodbrake ◽  
Alain Goriely ◽  
Arash Yavari
Keyword(s):  
Euclidean Space ◽  
Deformation Gradient ◽  
Deformation Tensor ◽  
Dimensional Euclidean Space ◽  
Multiplicative Decomposition ◽  
Mathematical Basis ◽  
Isometric Embeddings ◽  
Higher Dimensional ◽  
Mathematical Foundations ◽  
Central Tool

A central tool of nonlinear anelasticity is the multiplicative decomposition of the deformation tensor that assumes that the deformation gradient can be decomposed as a product of an elastic and an anelastic tensor. It is usually justified by the existence of an intermediate configuration. Yet, this configuration cannot exist in Euclidean space, in general, and the mathematical basis for this assumption is on unsatisfactory ground. Here, we derive a sufficient condition for the existence of global intermediate configurations, starting from a multiplicative decomposition of the deformation gradient. We show that these global configurations are unique up to isometry. We examine the result of isometrically embedding these configurations in higher-dimensional Euclidean space, and construct multiplicative decompositions of the deformation gradient reflecting these embeddings. As an example, for a family of radially symmetric deformations, we construct isometric embeddings of the resulting intermediate configurations, and compute the residual stress fields explicitly.

A Note on Covering by Convex Bodies

2009 ◽  
Vol 52 (3) ◽  
pp. 361-365 ◽  
Author(s):  
Fejes Tóth Gábor
Keyword(s):  
Convex Body ◽  
Euclidean Space ◽  
Convex Bodies ◽  
Dimensional Euclidean Space ◽  
Classical Theorem ◽  
Lattice Arrangement

AbstractA classical theorem of Rogers states that for any convex body K in n-dimensional Euclidean space there exists a covering of the space by translates of K with density not exceeding n log n + n log log n + 5n. Rogers’ theorem does not say anything about the structure of such a covering. We show that for sufficiently large values of n the same bound can be attained by a covering which is the union of O(log n) translates of a lattice arrangement of K.

scholarly journals Approximation Properties of Random Polytopes Associated with Poisson Hyperplane Processes

2014 ◽  
Vol 46 (4) ◽  
pp. 919-936
Author(s):  
Daniel Hug ◽  
Rolf Schneider
Keyword(s):  
Convex Body ◽  
Euclidean Space ◽  
Hausdorff Distance ◽  
Dimensional Euclidean Space ◽  
Approximation Properties ◽  
Random Polytopes ◽  
Directional Distribution ◽  
Zero Cell

We consider a stationary Poisson hyperplane process with given directional distribution and intensity in d-dimensional Euclidean space. Generalizing the zero cell of such a process, we fix a convex body K and consider the intersection of all closed halfspaces bounded by hyperplanes of the process and containing K. We study how well these random polytopes approximate K (measured by the Hausdorff distance) if the intensity increases, and how this approximation depends on the directional distribution in relation to properties of K.

A separation theorem for totally-sewn 4-polytopes

2015 ◽  
Vol 52 (3) ◽  
pp. 386-422
Author(s):  
T. Bisztriczky ◽  
F. Fodor
Keyword(s):  
Convex Body ◽  
Euclidean Space ◽  
Interior Point ◽  
Separation Theorem ◽  
Dimensional Euclidean Space ◽  
Separation Problem ◽  
Minimum Number

The Separation Problem, originally posed by K. Bezdek in [1], asks for the minimum number s(O, K) of hyperplanes needed to strictly separate an interior point O in a convex body K from all faces of K. It is conjectured that s(O, K) ≦ 2d in d-dimensional Euclidean space. We prove this conjecture for the class of all totally-sewn neighbourly 4-dimensional polytopes.

scholarly journals On a Measure of Asymmetry of Convex Bodies

1962 ◽  
Vol 58 (2) ◽  
pp. 217-220 ◽  
Author(s):  
E. Asplund ◽  
E. Grosswald ◽  
B. Grünbaum
Keyword(s):  
Convex Body ◽  
Euclidean Space ◽  
Present Note ◽  
Convex Bodies ◽  
Dimensional Euclidean Space ◽  
Measure Of Asymmetry ◽  
Measures Of Asymmetry

In the present note we discuss some properties of a ‘measure of asymmetry’ of convex bodies in n-dimensional Euclidean space. Various measures of asymmetry have been treated in the literature (see, for example, (1), (6); references to most of the relevant results may be found in (4)). The measure introduced here has the somewhat surprising property that for n ≥ 3 the n-simplex is not the most asymmetric convex body in En. It seems to be the only measure of asymmetry for which this fact is known.

scholarly journals APPLICATION OF THE THEORY OF OPTIMAL SET PARTITIONING BEFORE BUILDING MULTIPLICATIVELY WEIGHTED VORONOI DIAGRAM WITH FUZZY PARAMETERS

2020 ◽  
Vol 6 (2(71)) ◽  
pp. 30-35
Author(s):  
O.M. Kiseliova ◽  
O.M. Prytomanova ◽  
V.H. Padalko
Keyword(s):  
Euclidean Space ◽  
Finite Number ◽  
Nonsmooth Optimization ◽  
Voronoi Diagram ◽  
Optimization Problems ◽  
Optimal Location ◽  
Set Partitioning ◽  
Dimensional Euclidean Space ◽  
Optimal Set ◽  
Fuzzy Parameters

An algorithm for constructing a multiplicatively weighted Voronoi diagram involving fuzzy parameters with the optimal location of a finite number of generator points in a limited set of n-dimensional Euclidean space 𝐸𝑛 has been suggested in the paper. The algorithm has been developed based on the synthesis of methods of solving the problems of optimal set partitioning theory involving neurofuzzy technologies modifications of N.Z. Shor 𝑟 -algorithm for solving nonsmooth optimization problems.

scholarly journals Two finiteness theorems in the Minkowski theory of reduction

1972 ◽  
Vol 14 (3) ◽  
pp. 336-351 ◽  
Author(s):  
P. W. Aitchison
Keyword(s):  
Convex Body ◽  
Euclidean Space ◽  
Quadratic Forms ◽  
Positive Definite ◽  
Dimensional Euclidean Space ◽  
Symmetric Convex Body ◽  
Symmetric Convex ◽  
Reduction Theory ◽  
Positive Definite Quadratic Form ◽  
Finiteness Theorems

Minkowski proved two important finiteness theorems concerning the reduction theory of positive definite quadratic forms (see [6], p. 285 or [7], §8 and §10). A positive definite quadratic form in n variables may be considered as an ellipsoid in n-dimensional Euclidean space, Rn, and then the two results can be investigated more generally by replacing the ellipsoid by any symmetric convex body in Rn. We show here that when n≧3 the two finiteness theorems hold only in the case of the ellipsoid. This is equivalent to showing that Minkowski's results do not hold in a general Minkowski space, namely in a euclidean space where the unit ball is a general symmetric convex body instead of the sphere or ellipsoid.

scholarly journals Approximation Properties of Random Polytopes Associated with Poisson Hyperplane Processes

2014 ◽  
Vol 46 (04) ◽  
pp. 919-936 ◽  
Author(s):  
Daniel Hug ◽  
Rolf Schneider
Keyword(s):  
Convex Body ◽  
Euclidean Space ◽  
Hausdorff Distance ◽  
Dimensional Euclidean Space ◽  
Approximation Properties ◽  
Random Polytopes ◽  
Directional Distribution ◽  
Zero Cell

We consider a stationary Poisson hyperplane process with given directional distribution and intensity ind-dimensional Euclidean space. Generalizing the zero cell of such a process, we fix a convex bodyKand consider the intersection of all closed halfspaces bounded by hyperplanes of the process and containingK. We study how well these random polytopes approximateK(measured by the Hausdorff distance) if the intensity increases, and how this approximation depends on the directional distribution in relation to properties ofK.

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