数学物理学报(英文版) ›› 2025, Vol. 45 ›› Issue (2): 473-492.doi: 10.1007/s10473-025-0211-x
Jing Zhang1, Zechun Hu2, Wei Sun3,*
Jing Zhang1, Zechun Hu2, Wei Sun3,*
摘要: Let I be the set of all infinitely divisible random variables with finite second moments, I0={X∈I:Var(X)>0}, PI=infX∈IP{|X−E[X]|≤√Var(X)} and PI0=infX∈I0P{|X−E[X]|<√Var(X)}. Firstly, we prove that PI≥PI0>0. Secondly, we find the exact values of infX∈JP{|X−E[X]|≤√Var(X)} and infX∈JP{|X−E[X]|<√Var(X)} for the cases that J is the set of all geometric random variables, symmetric geometric random variables, Poisson random variables and symmetric Poisson random variables, respectively. As a consequence, we obtain that PI≤e−1∞∑k=0122k(k!)2≈0.46576 and PI0≤e−1≈0.36788.
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