Formal Mathematician - Fully Remote | Up to $110/hr Part-time

mercor; San Francisco (CA); Hybrid; CAD 177,000 - 216,000; Part time

Job summary

Mercor is seeking a Lean Engineer with a strong background in formal mathematics to work remotely on Lean 4 and mathlib, focusing on theorem proving and formalization of mathematical statements. The role is a contract engagement with 20–40 hours per week and collaboration with AI/ML-related research teams.

You will draft correct Lean statements, review AI-generated proofs, and help establish guidelines for proof quality and mathlib conventions in a collaborative lab environment.

Qualifications

• Hands-on experience writing formal proofs in Lean 4.
• Comfort with mathlib and Lean 4 tactics.
• Strong background in proof-based mathematics or logic.
• Ability to turn statements and proofs into correct formal statements and proofs.

Responsibilities

• Write correct, idiomatic Lean 4 statements and proofs that compile against current mathlib.
• Formalize natural-language mathematics from competition problems and textbook results to research-level lemmas.
• Review AI-generated Lean statements and proofs and provide clear, specific feedback.
• Help define guidelines and rubrics for proof quality and mathlib conventions.
• Collaborate with Lean engineers and researchers to maintain consistent standards and elevate quality.

Skills

Lean 4

Mathlib

Formal proofs

Lean tactics

Communication

Education

Degree in Mathematics/CS

Tools

Lean 4

Mathlib

Job description

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 Details

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.