Annali di Matematica Pura ed Applicata ( IF 1 ) Pub Date : 2021-02-27 , DOI: 10.1007/s10231-021-01080-y Bernardo González Merino
In this article, we show the following result: If C is an n-dimensional convex and compact subset, \(f:C\rightarrow [0,\infty )\) is concave, and \(\phi :[0,\infty )\rightarrow [0,\infty )\) is a convex function with \(\phi (0)=0\), we then characterize the class of sets and concave functions that attain the supremum
$$\begin{aligned} \sup _{C,f}\int _C\phi (f(x)){\text {d}}x, \end{aligned}$$where the supremum ranges over all sets C with n-dimensional volume \(|C|=c\) and the additional condition that \(f(x_{C,f})=k\) for some point \(x_{C,f}\in C\) that we introduce in the article, for two nonnegative constants \(c,k>0\). As a consequence, we extend some results of Milman and Pajor in (Adv Math 152(2):314–335, 2000) and some in (Mediterr J Math, 2020, Thm. 1.2). Besides, we also obtain some new estimates on the volume of particular sections of a convex set K passing through a new point of K.
中文翻译:
通过一个新的中心估计具有凸性的函数的平均值
在本文中,我们显示以下结果:如果C是n维凸和紧子集,\(f:C \ rightarrow [0,\ infty} \)是凹面,而\(\ phi:[0,\ infty)\ rightarrow [0,\ infty)\)是具有\(\ phi(0)= 0 \)的凸函数,然后我们描述达到最高的集合和凹函数的类别
$$ \ begin {aligned} \ sup _ {C,f} \ int _C \ phi(f(x)){\ text {d}} x,\ end {aligned} $$其中在所有集合C上具有n维空间\(| C | = c \)的最高值,并且对于某个点\(x_ {C ,f} \在本文中介绍的C \)中,用于两个非负常量\(c,k> 0 \)。结果,我们将Milman和Pajor的一些结果扩展到(Adv Math 152(2):314-335,2000)中,并扩展一些结果(Mediterr J Math,2020,Thm。1.2)。此外,我们还获得了关于凸集K穿过新点K的特定部分的体积的一些新估计。