1. As the other reply said, we just mean an ODE solver whose internal operations are a detail we don't need to worry about. 2. This paper only had proofs of co

1. As the other reply said, we just mean an ODE solver whose internal operations are a detail we don't need to worry about. 2. This paper only had proofs of concepts and toy demos. But our follow-up paper, FFJORD [https://arxiv.org/abs/1810.01367 https://arxiv.org/abs/1810.01367] we used the continuous normalizing flows to get SOTA efficiently sample-able density models.