> if you want to learn about deep learning, just learn about neural networks. It's the same thing.

Hi, could you explain this further? From my limited understanding, couldn't deep learning be achieved without neural networks? If we define deep learning as something like automatic feature extraction on one level of hierarchy in order to aid classification at a different level. I understand that you are saying that neural networks are the most common tool used, however what is the reason for this -- couldn't one also stack the results of other algorithms (decision trees, SVM, etc.) into a hierarchy of features?