[_a_a_a_]

Maybe, maybe not https://en.wikipedia.org/wiki/Backpropagation#History

It's odd how blatantly simple stuff can be so difficult for even experts to see sometimes.

[roenxi]

We might note that it wouldn't have been useful if it was discovered much earlier. There is a minimum amount of computation required to get good results out of neural nets that we've only been crossing relatively recently. From some perspectives the technique could be argued as the most computationally intensive approach to problem solving humans have employed to date.