say that it just has to have multiple layers that can be multiple steps in a feed-forward differentiable computation that can be multiple layers in a graphical model there's a lot of ways that you could satisfy me that something has multiple steps that are each parameterised separately I think of gradient descent as being all about that other piece the how do you actually update the parameters piece so you can imagine having a deep model like a convolutional net and training it with something like evolution or a genetic