[nused]

Thanks for the mention. We've re-organized the material and updated the submissions by splitting into three parts. We wanted to extend the content but felt that in its original form the article was too dense. The new structure consists of three related but more self-contained articles to help articulate the key differences:

Overview: https://arxiv.org/abs/1905.01518

Systems perspective: https://arxiv.org/abs/1905.01517

Correctness/theoretical perspective: https://arxiv.org/abs/1905.01302