Lean Engineer, Formal Mathematics – Lean 4, Mathlib, Theorem Proving

Job Description:

• Write correct, idiomatic Lean 4 statements and proofs compiling against current mathlib
• Formalize natural-language mathematics, including competition problems, textbook results, and research-level lemmas
• Review AI-generated Lean statements and proofs
• Identify failures or proofs that establish the wrong thing and provide clear written feedback
• Help define guidelines and rubrics for proof quality, statement fidelity, and mathlib conventions
• Collaborate with Lean engineers and lab researchers to maintain consistent standards
• Work on projects training and enhancing AI systems

Requirements:

• Hands-on experience writing formal proofs in Lean 4
• Comfort with mathlib and Lean 4 tactics, including finding and using appropriate lemmas
• Strong background in proof-based mathematics, theoretical computer science, or logic, through a degree or research record
• Ability to convert written statements and proofs into correct formal statements and checking proofs
• Availability for at least 20 hours per week during weekdays
• Clear written communication and ability to explain proof strategy and formalization choices precisely
• Nice to have: experience with Coq/Rocq, Isabelle, Agda, Haskell, Lean metaprogramming, or AI-for-math work
• Unable to support H1-B or STEM OPT candidates at this time

Benefits:

• W-2 employment with Cincinnatus LLC (or appropriate international entity)
• Payroll, benefits, and compliance provided by the employer of record
• Fully remote work
• Flexible schedule / work on your own schedule
• Weekly payments via Stripe or Wise
• Opportunity to collaborate with leading researchers
• Referral payments of up to $1,760 for each successful referral