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arXiv 2602.18293math.OCmath.PR
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关于 $p$-Wasserstein 质心的 $q$-可积性

On the $q$-integrability of $p$-Wasserstein barycenters

Technische Universität München(慕尼黑工业大学);Università degli studi di Milano(米兰大学)

Camilla Brizzi, Lorenzo Portinale

AI总结:

本文研究了 $p$-Wasserstein 质心的 $q$-可积性,证明了在某些条件下 $W_p$-质心的正则性,并探讨了支持集几何结构对结果的影响。

摘要:

我们研究了 $N$ 个在 $\mathbb{R}^d$ 上的概率测度的质心密度在 $p$-Wasserstein 度量下的 $L^q$-正则性($1<p<\infty$)。根据第一作者与合作者之前的结果,如果其中一个边缘是绝对连续的,那么 $W_p$-质心也是。接下来自然的问题是,是否在任何 $q>1$ 的情况下,边缘的 $L^q$-正则性也会被保留,如同在经典情况($p=2$)下的 Agueh--Carlier 情况,或者在 $W_p$-测地线($N=2$)中。这里我们证明,如果其中一个边缘属于 $L^q$,并且所有边缘的支持集满足合适的几何假设,则情况是如此。然而,我们表明,一旦 $N>2$,就可以找到 $W_p$-质心不是 $q$-可积的例子,即使其中一个边缘是紧支撑且有界的,这突显了支持集几何结构的作用。此外,我们提供了一个关于 $L^q$-范数的一般估计,包括对奇点来源的详细研究,并以 Agueh--Carlier 的方式用相关的 Kantorovich 劽量来表征 $W_p$-质心。最后,我们明确计算了通过特殊仿射变换得到的测度的 $W_p$-质心。在这种情况下,正则性在没有任何额外支持假设的情况下都成立。

英文摘要:

We study the $L^q$-regularity of the density of barycenters of $N$ probability measures on $\mathbb{R}^d$ with respect to the $p$-Wasserstein metric ($1<p<\infty$). According to a previous result by the first author and collaborators, if one marginal is absolutely continuous, so is the $W_p$-barycenter. The next natural question is whether the $L^q$- regularity on the marginals is also preserved for any $q > 1$, as in the classical case ($p=2$) of Agueh--Carlier, or for $W_p$-geodesics ($N=2$). Here we prove that this is the case if one marginal belongs to $L^q$ and the supports of all the marginals satisfy suitable geometric assumptions. However, we show that, as soon as $N>2$, it is possible to find examples of $W_p$-barycenters which are not $q$-integrable, even if one marginal is compactly supported and bounded, thus highlighting the role played by the geometry of the supports. Furthermore, we provide a general estimate of the $L^q$-norm, including a detailed study of the sources of singularities, and a characterization of the $W_p$-barycenters à la Agueh--Carlier in terms of the associated Kantorovich potentials. Finally, we explicitly compute the $W_p$-barycenters of measures obtained as push-forward of special affine transformations. In this case, regularity holds without any additional requirement on the supports.

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