Awesome article.<p>My take on this is that &#x27;interesting&#x27; graph problems tend to be NP-(.*), or reduce to a handful of well-known standards.  Some of these standards, like breadth-first traversal, work quickly and are therefore standard interview questions.  Other standard solutions, like page-rank, are effectively eigenvalue problems which take N^3 time to find the true solution.  N^3 is generally too slow for large-scale production systems, though, so we end up introducing some randomness and battering the algorithm into an almost-linear time approximation algorithm that can run on a thousand machines no problem; this is where Pregel comes from.<p>As someone who loves playing with graph algorithms, I would absolutely love to be wrong in this world-view, and learn that mine eyes have been carefully shielded from the beautiful variety of graph problems that aren&#x27;t in one of these three classes...  So I&#x27;ll make a resolution to try to keep my eyes open for surprises in 2016.