title: How to handle terminal nodes in Monte Carlo Tree Search?
body: <p>When my tree has gotten deep enough that terminal nodes are starting to be selected, I would have assumed that I should just perform a zero-move "playout" from it and back-propagate the results, but the <a href="http://mcts.ai/pubs/mcts-survey-master.pdf" rel="nofollow noreferrer">IEEE survey of MCTS methods</a> indicates that the selection step should be finding the "most urgent expandable node" and I can't find any counterexamples elsewhere. Am I supposed to be excluding them somehow? What's the right thing to do here?</p>