How does error get back propagated through pooling layers? [closed]
Solution 1:
A layer doesn't need to have weights in order to back-prop.
You can compute the gradients of a global avg pool w.r.t the inputs - it's simply dividing by the number of elements pooled.
It is a bit more tricky when it comes to max pooling: in that case, you propagate gradients through the pooled indices. That is, during back-prop, the gradients are "routed" to the input elements that contributed the maximal elements, no gradient is propagated to the other elements.