suboptimal because what you want is you want a single model to output your word vectors or to interpret the language that can look at both the left and the right at the same time and then incorporate information from both of them simultaneously and not just at the end by concatenation this is what Birth does it's a bird here and this is kind of what they claim is the new contribution bird at each in each layer here of the model D D let's look at this and for a particular token they look at all of the context so every every other