Lean Engineer, Formal Mathematics (Lean 4, Mathlib, Theorem Proving)

• Write correct, idiomatic Lean 4 statements and proofs that compile against current mathlib, across areas such as algebra, analysis, number theory, combinatorics and logic.
• Formalize natural-language mathematics, from competition problems and textbook results to research-level lemmas, paying close attention to whether the formal statement matches the original.
• Review AI-generated Lean statements and proofs, find where they fail or prove the wrong thing, and give clear, specific written feedback.
• Help define guidelines and rubrics for proof quality, statement fidelity and mathlib conventions.
• Collaborate with other Lean engineers and the lab's researchers to keep standards consistent and keep raising the quality bar.

• Hands-on experience writing formal proofs in Lean 4, for example mathlib contributions, a formalization project, a Lean library or tool, or autoformalization work.
• Comfort with mathlib and Lean 4 tactics, and with finding and using the right lemmas.
• A strong background in proof-based mathematics, theoretical computer science or logic, through a degree or a research record.
• The ability to turn a written statement and proof into a correct formal statement and a proof that checks.
• Ability to engage reliably for at least 20 hours/week during weekdays.
• Clear written communication and the ability to explain proof strategy and formalization choices precisely.

• Experience with other proof assistants or dependently typed languages (Coq/Rocq, Isabelle, Agda, Haskell), Lean metaprogramming, or AI-for-math work such as LLM provers, Lean agent environments, or benchmarks like miniF2F, ProofNet or PutnamBench.

Project and contracting process: the hiring partner. Applications continue on the provider's website.