ChaCha I think it's part of lecture and then we'll dive in with with that later so first question is there's also we can have P of X and P is a mixture of gaussians how you can simply of X to begin with yeah it's a very observation it's not exactly our assumption the assumption more precise is that we have a mixture model and that four components individual components in a mixture model we know how to encode efficiently but for the mixture model as a whole we might not know how to encode and now we have a scheme to do that especially if