this is what we call the encoder and this is a decoder so we so on the float on top of the flow model we define this encoder and decoder and the decoder is just the inverse of the flow with this identity covariance such as very small so that's what these two is ellipsoid on the left and their small circle on the right are so what why did we define this well the point is that if for a flow model is represents a differentiable function so if if you have some data point X and we had a very small amount of noise to it and then you