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

Mercor

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

Posted 10/11/2026part-timeRemote • United StatesMid-LevelSenior💰 $90 - $110 per hourWebsite

Core Competencies

Role fit

Core Competencies

Use this summary to align your resume positioning with the role.

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

Highest-signal resume keywords

Lean 4 Proof WritingMathlib FamiliarityProof-Based MathematicsClear Written CommunicationAI-For-Math Experience

ATS Keywords

Tailor your resume

Applicant Tracking System Keywords

Tip: use these terms in your resume and cover letter to boost ATS matches.

Hard Skills

Formal ProofsLean 4 TacticsMathematical FormalizationProof CheckingTheoretical Computer Science

Soft Skills

Written FeedbackCollaborationExplaining Proof Strategy

Tools & Technologies

MathlibCoqIsabelleAgdaHaskell

Industry Keywords

FormalizationProof QualityStatement FidelityLean MetaprogrammingAI Systems

Tech Stack

Tools & technologies

Haskell

About the role

Key responsibilities & impact

Write correct, idiomatic Lean 4 statements and proofs that compile 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 incorrect results, and provide specific written feedback
Help define guidelines and rubrics for proof quality, statement fidelity, and mathlib conventions
Collaborate with Lean engineers and 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
Availability for at least 20 hours per week during weekdays, with reliable engagement
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 require H1-B or STEM OPT sponsorship/support at this time

Benefits

Comp & perks

W-2 employment with payroll, benefits, and compliance through Cincinnatus LLC (or appropriate international entity)
Fully remote work
Flexible schedule; work can be completed on your own schedule
Weekly payments via Stripe or Wise based on services rendered
Opportunity to collaborate with leading researchers
Referral payments of up to $1,760 for each successful referral, subject to limits