> Code and math are similar to chess/go, where verification is (reasonably) easy
Verification for code would be a formal proof, and these are hard; with a few exceptions like seL4, most code does not have any formal proof. Games like chess and go are much easier to verify. Math is in the middle; it also needs formal proofs, but most of math is doing these formal proofs themselves, and even then there are still unproven conjectures.
Verification for code is just running it. Maybe "verification" was the wrong word. The model just needs a sense of code X leads to outcome Y for a large number of (high-quality) XY pairs, to learn how to navigate the space better, same as with games.
Verification for code would be a formal proof, and these are hard; with a few exceptions like seL4, most code does not have any formal proof. Games like chess and go are much easier to verify. Math is in the middle; it also needs formal proofs, but most of math is doing these formal proofs themselves, and even then there are still unproven conjectures.