That said, making the 19 adapter is a whole new task, and I think these tests should be converted to RTL eventually, so the approach described in the blog post is still valuable.
Did you use Chat GPT 3.5 or Chat GPT 4? GPT 4 solves this correctly when I ran it (but admittedly, by nature of the way it works non deterministically, it might have failed for you but worked for me)
My takeaway: modeling problems in minizinc correctly is exceptionally difficult for non-trivial problems. You can model it correctly, but you'll likely still need to add additional "constraints" that improve the performance of the solver to the degree where it's even remotely usable to solve real problems.
It's a really interesting tool, but one of the reasons we thought it might be useful for this problem is so that non-technical people could easily change the constraints and play with the costs for different operations. I don't think it's particularly good for that, at least in this problem domain.
They do actually talk about this idea in the talk. The "shortest possible program" that can be used to describe the music is undecidable, but there is a short description, in the case you just described it's unknown to the listener.
That said, making the 19 adapter is a whole new task, and I think these tests should be converted to RTL eventually, so the approach described in the blog post is still valuable.