in the vocabulary this formulation is impractical because the cost of computing the gradient is proportional to W which is often large and that's 10 to the 5 to 10 to the 7 terms so many 10 like tens of millions of terms in your vocabulary that's just not feasible right so people have been you know sort of trying different ways to get around very very large number of classes and here it seems that that is really our bottleneck in the previous paper they've already shown that this objective can give you very good word representation