I&#x27;m not sure how close you are to working with RL&#x2F;ML, possibly more than me! However, I don&#x27;t think you it is useful to talk about the state of the field so broadly. If you say &quot;supervised learning is well understood&quot;, I think you have a better chance of being right. The challenges that arise in taking sequential decisions, and learning from sequential observations is a lot harder, because all your data is temporally correlated.<p>Yeah we have algorithms for RL, but actually there are still many theoretical things we cannot prove and in practice do not work well. I am not intimately familiar, but one example is value iteration with a non-linear value function approximation.<p>I still maintain that RL is not well-understood, and I think evidence for that is that we don&#x27;t see many examples of RL in our phones, cameras, search engines, etc. (which is not the case for supervised learning).