# 對稱概率分佈

${\displaystyle f(x_{m}-\delta )=f(x_{m}+\delta )}$ ${\displaystyle {\text{for}}}$ 所有實數 ${\displaystyle \delta }$

## 攷

1. Ali, Mir M. (1980). "Characterization of the Normal Distribution Among the Continuous Symmetric Spherical Class". Journal of the Royal Statistical Society. Series B (Methodological). 42 (2): 162–164.