ural language uses a specialized part of the brain that we do not intimately understand. There is no objective &quot;best comment&quot;, and subjectively evaluating the quality of commentary engages yet more specialized brain areas on a choice of many different axes. Do we care about correctness, insight, expressiveness, personality, variety? And under which circumstances? The final comment in an article may read very differently to a standalone one. Machine learning translation commonly uses metrics such a