ThmDex – An index of mathematical definitions, results, and conjectures.
Result R3516 on D5102: Basic expectation
Signed basic expectation of almost surely zero random number is zero
Formulation 0
Let $P = (\Omega, \mathcal{F}, \mathbb{}P)$ be a D1159: Probability space.
Let $X : \Omega \to [-\infty, \infty]$ be an D3066: Absolutely integrable random number on $P$ such that
(i) $X =_{\mathsf{a.s.}} 0$
Then \begin{equation} \mathbb{E}(X) = 0 \end{equation}
Formulation 1
Let $P = (\Omega, \mathcal{F}, \mathbb{}P)$ be a D1159: Probability space.
Let $X : \Omega \to [-\infty, \infty]$ be an D3066: Absolutely integrable random number on $P$ such that
(i) $X =_{\mathsf{a.s.}} 0$
Then \begin{equation} \int_{\Omega} X \, d \mathbb{P} = 0 \end{equation}
Proofs
Proof 0
Let $P = (\Omega, \mathcal{F}, \mathbb{}P)$ be a D1159: Probability space.
Let $X : \Omega \to [-\infty, \infty]$ be an D3066: Absolutely integrable random number on $P$ such that
(i) $X =_{\mathsf{a.s.}} 0$
This result is a particular case of R1903: Basic integral of almost everywhere zero function is zero. $\square$