Max-pooling VS Sum-pooling
<p>I have <sub>partially</sub> understood Max-pooling, after reading <a href="http://deeplearning.net/tutorial/lenet.html" rel="noreferrer">Convolutional Neural Networks (LeNet)</a>:</p>

<blockquote>
  <p>Another important concept of CNNs is max-pooling, which is a form of
  non-linear down-sampling. Max-pooling partitions the input image into
  a set of non-overlapping rectangles and, for each such sub-region,
  outputs the maximum value.</p>
</blockquote>

<p>What about Sum-pooling? I couldn't find any easy to understand article.</p>