I know recursion is everywhere but I recently noticed it in very unusual place('unusual' in the way we see), I hail from India, we studied in our childhood about road less taken, the way I see, everyone has to take so important decisions in yheir life, one such decission is about career, in India road less taken in career paths is everything other than orthodox education, I too the dreaded road "Education", next decission is to choose stream and there the road less taken is anything other that "Engineering (or medicne) " and I took (*as expected) engineering, after taking computers (which is the dreaded road now) next decision is what next? Dreaded road is job, but this time I chose take a road little less traveled in CS. Then I next decission was to choose the research stream the road less taken here (NOW) is systems as AI is in its prime and everyone whants to ride the wave, but I chose Systems in research, after all these my point how how boolean function is called recursively (in the sense of construct) and as a systems programmer I realize the importance of optimizing how I answer these functions quick and accurate. This is one such boolean function but I am sure you can find many in our path till here so It is better to realize what these functions are optimize then as a good Programmer of your own Life.