Self-supervised backprop in deep autoencoders
	• We can put extra hidden layers between the input and the bottleneck and between the bottleneck and the output. – This gives a non-linear generalization of PCA • It should be very good for non-linear dimensionality reduction. – It is very hard to train with backpropagation – So deep autoencoders have been a big disappointment. • But we recently found a very effective method of training them which will be described next week.