February 8, 2026
Proofs, dragons, and spicy nostalgia
Formally Verifying PBS Kids with Lean4
Math nerds prove PBS Kids puzzles; nostalgia clashes with “tech ain’t fun” vibes
TLDR: A blogger used the Lean proof language to rigorously model a Cyberchase puzzle, turning kids’ TV math into formal strategy. Comments erupted with nostalgia and a debate over whether this is joyful geekery or proof that tech lost its fun, with jokes about “peer‑reviewing Motherboard.”
A blogger just used the math-proof language Lean (leanprover.github.io) to model a classic Cyberchase episode—yes, the PBS Kids show with dragons and the villain voiced by Christopher Lloyd. The internet didn’t stay calm. While some cheered, “Finally, childhood math gets grown‑up receipts,” others rolled their eyes: formal proofs for a kids’ show? Overengineering or pure joy? That’s the mood swing.
Nostalgia flooded the comments as 2000s kids remembered racing home to watch Matt, Jackie, and Inez discover math from scratch. But the spiciest take came from the “tech is no longer fun” camp, arguing we don’t even make upbeat AI shows anymore and that this project is a coping mechanism for modern tech cynicism. Lean fans clapped back, saying this is exactly the point: proof tools make code safer, and turning a dragon puzzle into a bulletproof strategy is like catching bugs before they bite. The jokes were relentless: “Motherboard has finally been peer‑reviewed,” “Hacker is just a bad unit test,” and “Red dragon = production DB in disguise.”
Whether you loved Cyberchase or you fear math like the red dragon, the crowd’s split: adorable overkill vs. glorious geek art. Either way, the comment section ate it up.
Key Points
- •The article models a Cyberchase episode’s turn-based dragon game in Lean to demonstrate formal verification.
- •Interactive theorem proving is presented as composing proofs from verified facts down to mathematical axioms.
- •Lean is used to encode game rules, functions, and strategies, employing types like Nat and equality semantics.
- •SMT solvers are contrasted with Lean’s approach; they use heuristics but are working to emit formal proof artifacts.
- •The game features 15 dragons (14 green, 1 red), with players removing 1–3 per turn; taking the red dragon causes an immediate loss.