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

Mercor

. Write correct, idiomatic Lean 4 statements and proofs compiling against current mathlib .

Posted 10/17/2026part-timeRemote • United StatesMid-LevelSenior💰 $90 - $110 per hourWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates expertise in writing formal proofs in Lean 4 and a strong background in proof-based mathematics, theoretical computer science, or logic. Capable of providing clear feedback and collaborating effectively with engineers and researchers to enhance AI systems and maintain high standards in mathematical formalization.

Highest-signal resume keywords

Formal Proof Writing In Lean 4Mathlib FamiliarityProof-Based Mathematics BackgroundClear Written CommunicationAI-For-Math Experience

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

Lean 4Formal ProofsMathematical FormalizationProof CheckingLean TacticsFinding LemmasProof StrategyCoq/Rocq ExperienceIsabelle ExperienceAgda Experience

Soft Skills

Clear CommunicationFeedback ProvisionCollaboration

Tools & Technologies

MathlibLean MetaprogrammingAI Systems

Industry Keywords

AlgebraAnalysisNumber TheoryCombinatoricsLogicTheoretical Computer Science

Tech Stack

Tools & technologies

Haskell

About the role

Key responsibilities & impact

Write correct, idiomatic Lean 4 statements and proofs compiling against current mathlib
Work across algebra, analysis, number theory, combinatorics, and logic
Formalize natural-language mathematics, including competition problems, textbook results, and research-level lemmas
Review AI-generated Lean statements and proofs
Identify failures or cases where proofs establish the wrong claim
Provide clear, specific 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 and improve quality
Work on projects training and enhancing AI systems

Requirements

What you’ll need

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 turn written statements and proofs into correct formal statements and checking proofs
Ability to engage reliably 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
Must not be an H1-B or STEM OPT candidate, as sponsorship/support is unavailable

Benefits

Comp & perks

Part-time schedule of at least 20 hours per week, with the option to increase to up to 40 hours per week
Fully remote work on your own schedule
W-2 employment, payroll, benefits, and compliance through Cincinnatus LLC or an appropriate international entity
Weekly payments via Stripe or Wise based on services rendered
Competitive pay
Opportunity to collaborate with leading researchers
Opportunity to help shape the next generation of AI systems
Referral payments of up to $1,760 per successful referral