pre training stage and a training stage so in the pre training stage this is over here su provides contrastive in the pre training stage it simply tries to learn these representations right like over like down here such that without the decision boundaries class think images of the same class are close together and images of different classes are far apart which notice the the subtle difference right to the cross-entropy loss where you just care about them being on one or the other side of a decision boundary and in stage this so