birth and then basically bert really pushed this auto encoding language model pre-training which made it so successful and now this paper excel net wants to like combine the best of both of them and in order to understand what's the best of both of them so what's good at birth we've already seen it can actually draw information from all of the context of the words it's trying to predict but what is the kind of pitfall of birth and they they actually put this really nicely in an example they give way further down where they say comparison