In principle, Math proofs are another relatively easy to verify problem. In the extreme case, you can express any math proof as a computer-verifiable formalism — no intelligence necessary. Step back one step, and you could have a relatively weak model translate a proof into verifiable formalism and then use a tool call to run the verification. Coming up with the proof is an expensive search process, while verifying it is more mechanical. Even if it is not completely trivial to make the proof computer-verifiable, it might still be a vastly easier task compared to finding the proof in the first place.