It seems to me this is only useful for self-improvement up to the point of accomplishing objectives and problems that humans have already clearly defined, solved and mapped. For example, "At checkpoints, a stronger evaluator can replace the old one if it performs better on trusted ground-truth examples." - if they're a trusted ground-truth, they must be rigorous. If we're attempting to solve problems that humans have not already solved, where do you get your ground-truth examples? It's not like the AI is going to be able to generate these for you if it has never seen a solution to the problem.

I can definitely see the argument that this allows us to train models faster and converge faster, because if you scale difficulty of evaluation alongside the learners capabilities, it spends a lot less time floudering around. It basically works out to be loss minimization through strategic ordering of the training data. Is that the goal here though? Or is the goal recursive self-improvement and solving problems that are currently outside of reach? Because it doesn't feel like the latter would be possible with this design.

For example, how do you quantify "the evaluation gets -harder- as the agent gets better". Harder, how? In what direction? Via what criteria or measure?