Gated Linear Unit

A Gated Linear Unit, or GLU computes:

$$ \text{GLU}\left(a, b\right) = a\otimes \sigma\left(b\right) $$

It is used in natural language processing architectures, for example the Gated CNN, because here $b$ is the gate that control what information from $a$ is passed up to the following layer. Intuitively, for a language modeling task, the gating mechanism allows selection of words or features that are important for predicting the next word. The GLU also has non-linear capabilities, but has a linear path for the gradient so diminishes the vanishing gradient problem.