Interestingly, there was a Show HN last year formalizing PM in Lean (https://news.ycombinator.com/item?id=43797256 https://news.ycombinator.com/item?id=43797256

Interestingly, there was a Show HN last year formalizing PM in Lean (https://news.ycombinator.com/item?id=43797256 https://news.ycombinator.com/item?id=43797256), and the Principia Rewrite project (https://www.principiarewrite.com https://www.principiarewrite.com) verified all 189 propositional logic theorems (sections 1-5) in Coq against the original proof sketches