uncommon if we have a good predictive model which makes H of X very low then it could be very high overhead for example our distribution over symbols the three symbols very peaked mostly on the first symbol because we can predict the next letter maybe very easily the next pixel very easily we're very peak distribution 90% of math then 5% 5% the entropy of this thing is roughly 0.5 but it will pay a penalty of +1 and in fact we send us a lot of time each thing is gonna cost us at least one because sending a bit sending anything across