back row and then with back probably have a much smoother much faster optimization trajectory so they looked at this and they they come to some some conclusions first of all so here's here's back prop basically saying back prop as we said you have the forward pass and there you simply compute these weighted averages and you you also pass them usually through some sort of nonlinear activation right and the cool thing about this is in artificial neural networks is that once the error comes in you can exactly reverse that so you can