You're right measuring the skill of a composer is hard, however as you say listener ratings and sales/streams would be a pretty good metric. Even for songs in t

You're right measuring the skill of a composer is hard, however as you say listener ratings and sales/streams would be a pretty good metric. Even for songs in the top 100 charts how high can an AI get? If all the top 10 songs were written by an AI that would be pretty convincing it was super human I think. On the issue of generalising alpha go learned go by watching human played games and by playing against itself and is now better than any human. So it's not true that a system is limited only to the skill of the examples it's shown, it's possible to design something which can surpass the examples it learned from.