What does this E symbol mean?
It is from the GAN paper.
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Uppercase "E" is one of the very few symbols in statistics that almost always have the same meaning: expected value. – Tim Aug 10 '17 at 06:51
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@tim thanks, maybe leave that as an answer so I can accept? – Nathan Aug 10 '17 at 07:48
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I love that we googled this exact thing, GAN paper and everything. – Script Kitty Jul 17 '18 at 22:07
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In mathematics and statistics many symbols are used to denote different things, e.g. $\pi$ does not always have to be the $3.14.15...$ constant. However the uppercase "E" (written in many forms, e.g. $\mathbb{E}, E, \mathrm{E}$) is almost always used in statistics to denote the expected value. In the case of your equation
$$ \mathbb{E}_{x\sim p_\text{data}(x)}\left( \log D(x) \right) $$
means: the expected value of $\log D(x)$ given $x$ distributed as $p_\text{data}(x)$.
Tim
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