We also have a more recent and slightly longer draft with additional explanations and GPU training results for ResNet 50 and DeepSpeech2:

"Demystifying Differentiable Programming: Shift/Reset the Penultimate Backpropagator" https://www.cs.purdue.edu/homes/rompf/papers/wang-preprint20...

The Lantern framework is available here: https://github.com/feiwang3311/Lantern