Rigorous proof verification within the informal approach
Ascertain whether rigorous verification of mathematical proofs can be achieved using informal, natural-language-based methods without grounding in formal systems, for example via language-model self-verification or self-correction.
References
Therefore, it is still an open question whether rigorous proof verification can be achieved within the informal approach.
— Formal Mathematical Reasoning: A New Frontier in AI
(2412.16075 - Yang et al., 20 Dec 2024) in State-of-the-art Math LLMs and Their Limitations — Lack of Correctness Verifiability (Section 2.1)