Like all punctuation: it's a choice. One that has made it's way into LLMs because they've injested a lot of actual books that were professionally type-set. Hu

Like all punctuation: it's a choice. One that has made it's way into LLMs because they've injested a lot of actual books that were professionally type-set. Humans typing online don't tend to use em-dash; LLMs often make the choice to do so. That makes it a very strong signal.