First seen by our source: 19 days ago
Lean Engineer - Formal Mathematics
@ Mercor
Toronto, Ontario
Overview
Mercor is hiring a contract Lean Engineer for formal mathematics, working remotely 20 to 40 hours a week at $90 to $110 per hour. The role writes and reviews Lean 4 statements and proofs against mathlib, formalizes mathematics from competition problems to research lemmas, and sets quality guidelines for an AI research lab.
Pay:
$90–$110 an hour
Responsibilities:
- Write Lean 4 statements and proofs that compile against mathlib
- Formalize natural-language mathematics faithfully
- Review AI-generated Lean proofs and give written feedback
- Help define proof quality and mathlib conventions guidelines
Requirements summary:
- Hands-on experience writing formal proofs in Lean 4
- Comfort with mathlib and Lean 4 tactics
- Strong background in proof-based mathematics, computer science or logic
- Available at least 20 hours a week on weekdays
- Clear written communication of proof strategy
Tools & skills
Source and dates
Source type not verified · manatal
- Employer posting date
- Not provided
- First seen by our source
- 2026-10-18
- Source record updated
- 2026-10-18
These dates describe the source record, not a live verification that the employer is still hiring. Check the original posting.
Job details
| Department | Research & science |
| Hours per week | 30 |
| Travel | air: none · ground: none |
| Work setting | Home |
| Position | Mostly sitting |
| Physical demands | physical low · computer high |
| Languages | English |
| Fields of study | Mathematics, Theoretical computer science, Logic |
Summary and details written by AI from the posting; the employer’s posting is the authority.
Mercor
Saved company profile
Historical company information from a saved The Jobs API profile (LinkedIn/Crunchbase fields). It is not live-verified; figures may have changed. Missing values remain unknown.
We connect human expertise with leading AI labs and enterprises to train frontier models.
Full company description
Mercor is defining the future of work. We connect human expertise with leading AI labs and enterprises to train frontier models.
- LinkedIn followers
- 654,507
- People associated on LinkedIn
- 5,250
- Reported office locations
- San Francisco, California 94105, US
- Business categories
- Employment
- Software
- Recruiting
- Data Collection and Labeling
- Artificial Intelligence (AI)
- Machine Learning
- Other recorded names
- Mercor
- Profile identifies a recruitment agency
- Yes
- Reported total investment
- 483,600,000
Currency and observation date were not supplied; this is not a current valuation or a funding round.
Mercor is defining the future of work. We connect human expertise with leading AI labs and enterprises to train frontier models.
| Field | Value |
|---|---|
| Industry | Software Development |
| Company size | 51-200 employees |
| Headquarters | San Francisco, California |
| Organization type | Privately Held |
| Year founded | 2023 |
| Open jobs on Jobsy | 1,626 |
| View page |
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 D'Angelo, Larry Summers, and Jack Dorsey.
Position: Lean Engineer, Formal Mathematics (Lean 4, Mathlib, Theorem Proving)
Type: Contract
Compensation: $90–$110/hour
Location: Remote
Commitment: 20–40 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 lab's 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 20–30 mins to complete)
- Upload resume
- AI interview based on your resume
- Submit form
Resources & Support
- For details about the interview process and platform information, please check: https://talent.docs.mercor.com/welcome
- For any help or support, reach out to: [email protected]
PS: Our team reviews applications daily. Please complete your AI interview and application steps to be considered for this opportunity.
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