distribution as to marginal corresponding to the joint distribution that you use for label data points but that's often not the case in practical scenarios because today said one label unlabeled data is usually something coming from some other data set or some other data source and you want to make sure you still transfer knowledge therefore that that's a suspect to assumption to make but in practice it can be there's a workaround using various kinds of filtering techniques that this paper proposes so next look at mix-match which is another very