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On directional convolution equivalent densities (2109.06336v2)
Published 13 Sep 2021 in math.PR, math.AP, and math.FA
Abstract: We propose a definition of directional multivariate subexponential and convolution equivalent densities and find a useful characterization of these notions for a class of integrable and almost radial decreasing functions. We apply this result to show that the density of the absolutely continuous part of the compound Poisson measure built on a given density $f$ is directionally convolution equivalent and inherits its asymptotic behaviour from $f$ if and only if $ f$ is directionally convolution equivalent. We also extend this characterization to the densities of more general infinitely divisible distributions on $\mathbb{R}d$, $d \geq 1$, which are not pure compound Poisson.