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

Mercor

$90-110/hrRemote20 hours a week
**Help a leading AI lab teach its models to write real, machine-checked mathematics in Lean.** # 1\. Overview A leading AI lab is looking for Lean engineers, formal mathematicians and proof engineers to help its AI models state and prove mathematics correctly.

About the role

Help a leading AI lab teach its models to write real, machine-checked mathematics in Lean.

# 1\. Overview

A leading AI lab is looking for Lean engineers, formal mathematicians and proof engineers to help its AI models state and prove mathematics correctly. You'll write and review Lean 4 proofs, turn informal math into precise formal statements, and help the lab's researchers judge whether a model's proof is not just accepted by the checker but actually proves the right thing. If you enjoy writing Lean, know your way around mathlib, and can explain why a formalization is faithful or subtly wrong, this role is for you. This is a part-time commitment of at least 20 hours per week, with the option to increase to up to 40 hours per week.

This is a W-2 employment position with Cincinnatus LLC (or appropriate international entity), with the opportunity to be placed at a leading AI lab as part of their extended workforce.

# 2\. Key Responsibilities

- Write correct, idiomatic Lean 4 statements and proofs that compile against current mathlib, across areas such as algebra, analysis, number theory, combinatorics and logic.

- Formalize natural-language mathematics, from competition problems and textbook results to research-level lemmas, paying close attention to whether the formal statement matches the original.

- Review AI-generated Lean statements and proofs, find where they fail or prove the wrong thing, and give 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 keep standards consistent and keep raising the quality bar.

# 3\. Core Qualifications

- Hands-on experience writing formal proofs in Lean 4, for example mathlib contributions, a formalization project, a Lean library or tool, or autoformalization work.

- Comfort with mathlib and Lean 4 tactics, and with finding and using the right lemmas. …

Official source: work.mercor.com. Details can change; the platform's page is the final word. How we check listings.

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