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

🔥 20 hours ago

🇺🇸 United States – Remote

💵 $90 - $110 / hour

⏱ Part Time

🟡 Mid-level

🟠 Senior

👷🏻‍♀️ Engineer

👻 Ghost score 10%

What it means: how likely this posting is sitting open without active hiring.How to read it: 60% or higher means we think this is a ghost. Lower scores are less of a worry.How we score it: age, reposts, open roles vs team size, how fast jobs close, and whether pay is listed.Fine print: an estimate from public data, not a judgment of the company. Real jobs can score high, so treat it as a hint, not a fact.

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Mercor

WebsiteLinkedInAll Job Openings

51 - 200 employees

Founded 2023

🔥 Funding within the last year

💰 $350M Series C - Mercor on 2025-10

Mercor is a company for which no descriptive text was provided in the input. Additional information (products, services, target customers, or industry specifics) is needed to create an accurate summary and select appropriate industries.

📋 Description

• Write correct, idiomatic Lean 4 statements and proofs compiling against current mathlib • Formalize mathematics from competition problems and textbooks to research-level lemmas • Review AI-generated Lean statements and proofs • Identify failed proofs or proofs that establish the wrong result • Provide clear, specific written feedback • Help define guidelines and rubrics for proof quality, statement fidelity, and mathlib conventions • Collaborate with Lean engineers and AI-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 mathematical statements and proofs into correct formal statements and machine-checked 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 require H1-B or STEM OPT support

🏖️ 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 own schedule • Part-time commitment with option to increase from at least 20 to up to 40 hours per week • Weekly payments via Stripe or Wise based on services rendered • Competitive pay • Collaboration with leading researchers • Opportunity to work on frontier AI systems • Referral payments of up to $1,760 per successful referral