What is: DropConnect?

DropConnect generalizes Dropout by randomly dropping the weights rather than the activations with probability $1-p$. DropConnect is similar to Dropout as it introduces dynamic sparsity within the model, but differs in that the sparsity is on the weights $W$, rather than the output vectors of a layer. In other words, the fully connected layer with DropConnect becomes a sparsely connected layer in which the connections are chosen at random during the training stage. Note that this is not equivalent to setting $W$ to be a fixed sparse matrix during training.

For a DropConnect layer, the output is given as:

$r = a \left(\left(M * W\right){v}\right)$

Here $r$ is the output of a layer, $v$ is the input to a layer, $W$ are weight parameters, and $M$ is a binary matrix encoding the connection information where $M\_{ij} \sim \text{Bernoulli}\left(p\right)$. Each element of the mask $M$ is drawn independently for each example during training, essentially instantiating a different connectivity for each example seen. Additionally, the biases are also masked out during training.