is in some sense that for the common filter if you think about it if you're on your common filter you find the mean everywhere that sequence of means is actually also the most likely sequence so there is no difference in a common filter between the maximum a posteriori and the means that you find at every step from these from the smoother not the filter from the smoother because you want the most likely full sequence so either account for everything why is that well think about it what if you do an exact calculation do an exact