Lean Engineer Formal Mathematics AI Trainer

About the job

Mercor connects elite creative and technical talent with leading AI research labs. Headquartered in San Francisco our investors include Benchmark General Catalyst Peter Thiel Adam DAngelo Larry Summers and Jack Dorsey .

Position: Lean Engineer Formal Mathematics (Lean 4 Mathlib Theorem Proving)

Type: Contract

Compensation: $90$110/hour

Location: Remote

Commitment: 2040 hours/week

Role Responsibilities

• Write correct idiomatic Lean 4 statements and proofs that compile against current mathlib . Cover areas such as algebra analysis number theory combinatorics and logic.
• Formalize natural-language mathematics from competition problems and textbook results to research-level lemmas. Ensure the formal statement matches the original.
• Review AI-generated Lean statements and proofs. Identify failures or incorrect proofs and provide clear specific written feedback.
• Help define guidelines and rubrics for proof quality statement fidelity and mathlib conventions.
• Collaborate with other Lean engineers and the labs researchers to maintain consistent standards and elevate quality.

Qualifications

Must-Have

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

Preferred

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

Compensation & Legal

• W-2 employment with Cincinnatus LLC .
• Equal Employment Opportunity employer.

Application Process (Takes 2030 mins to complete)

• Upload resume
• AI interview based on your resume
• Submit form

Resources & Support

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PS: Our team reviews applications daily. Please complete your AI interview and application steps to be considered for this opportunity.