[rusk]

have you ever spent a lot of time sifting through any non-trivially large set of data looking for a pattern. Sometimes you need precepts to help you narrow your scope of attention. Like, when you go to find the proverbial needle in a haystack, the surest way of finding the needle is to take a "bottom up" approach and sift the entire haystack. Or, you could use your knowledge of where you last saw the needle and do a rough search there. Or in the hope that the needle is the right kind of metal you might try using a magnet. Each of these might prove fruitless if your assumptions don't hold but they have a high probability vs their cost.