Symbols:E/Expectation

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Expectation

$\expect X$


Let $X$ be a discrete random variable.

The expectation of $X$ is written $\expect X$, and is defined as:

$\expect X := \ds \sum_{x \mathop \in \image X} x \map \Pr {X = x}$

whenever the sum is absolutely convergent, that is, when:

$\ds \sum_{x \mathop \in \image X} \size {x \map \Pr {X = x} } < \infty$


The $\LaTeX$ code for \(\expect X\) is \expect X .


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