Conditional Expectation

$$ E(X | Y) $$

The above equation means the conditional expected value of a random variable $X$ given a condition, $Y$.

Example

The following equation is from the BYOL paper:

$$ q^{*} = \mathbb{E}[z_{\xi}^{\prime} | z_{\theta}] $$

It means the conditional expected value of $z_{\xi}^{\prime}$ given $z_{\theta}$.