Mathematics and programming, with a proof assistant at hand.
- Collatz, but stop at the drop: two papers and their Lean 4 / Mathlib formalization. The question is not whether every start reaches 1, but whether every x > 1 eventually falls below itself.
- rud1: The rud1-language is sound all over, strict where we must, and fast where we can.
ISOLUTION B.V. - Amsterdam (NL)

