Steve Hsu has recently claimed[1] to have started a startup in stealth to solve the hallucination problem over a corpus as large as 10,000 pages of dense, college-level textbooks, to the point where it can answer the end-of-chapter questions in the textbook with almost 100% accuracy (albeit not math questions) - I hope without using the answer key. Not sure if their approach is more robust than Supabase[2] or similar approaches, and no indication of whether it might scale up to something on the order of a search engine corpus, but it's something.

[1] https://www.youtube.com/watch?v=peHkL_MaxTU&t=1558s [2] https://news.ycombinator.com/item?id=34695306