[EdHominem]

> In an alternative reality where the players agreed that they were creating a creative work together, and signed the copyright to it over contractually, would your attitude change?

Yes, that would probably be the same (in general) as any other work-for-hire.

> Can you talk a little bit about why a very short riff such as 10-12 notes of this [...] should be subject to copyright?

I imagine it is subject to copyright, a Haiku would be.

The grey areas here are that such a short sequence lends itself to brute-forcing which isn't creative and probably wouldn't result in a copyright, and that independent creators would each have their own copyright. You can't just generate all possible books (even if not combinatorially impossible) and block authors from writing them.

> I find this very very hard to believe. If I came up with simple rules for transcribing a chess game with notes and then discovered that for a particular chess game this was pleasant, you really don't think I could copyright that tune?

Your program to do this would be copyrightable, but it would only produce a machine-translation (by definition) of the chess game so while the end results (the tune) be copyrightable, it wouldn't be your copyright.

[logicallee]

thanks.