Hinton I would encourage that you go forward and read it if you want to get into auto-encoders it's basically how he used auto-encoders restricted Boltzmann machine and auto-encoders for dimensionality reduction and he actually compares this with PCA and the results that he gets is that with autoencoders he's able to reduce dimensions of nonlinear type of data so the results that he gets the patterns that he under lives were much better than he got for PCA within the field of autoencoders there's two different types of popular