[Discussion] What are the problems of the backpropagation algorithm? • r/MachineLearning

Two days ago, an article quoting Hinton who was saying that backprop is not necessarily the way to go for AI, generated lots of very cool discussion on this sub-reddit (here). The discussion mainly went in the direction of asking what are alternatives to backprop. In this discussion I would like us to answer the question: what are the problems of backprop? Here's my initial input: Problems that seem to be intrinsic to backprop: Problems that currently pose lots of difficulties and we're not sure are possible with backprop: Do you agree with these? What other problems have you noticed during your work?