GitHub - tchaumeny/KleeneTree: Construction of the Kleene tree in Lean Construction of the Kleene tree in Lean. Contribute to tchaumeny/KleeneTree development by creating an account on GitHub.

My first real Lean project: a formalization of the Kleene tree🌳

github.com/tchaumeny/Kl...

This is not my turf but I'd look at theorems like Sack's splitting to get an idea for a counter-example.