Lean 4 Formal Mathematics Engineer — Part Time (20–40h)

AI Trainer Jobs; United States; Remote; USD 65,000 - 95,000; Part time

Job summary

Cincinnatus LLC is seeking Lean engineers and formal mathematicians to help its AI lab state and prove mathematics in Lean 4. You will write and review Lean proofs, formalize statements from informal math, and provide precise feedback on AI-generated proofs. Part-time commitment of 20–40 hours per week with potential to increase.

The role involves collaborating with researchers to ensure fidelity, contribute to proof quality guidelines, and work with mathlib across multiple areas of mathematics.

Qualifications

• Hands-on experience writing formal proofs in Lean 4, including mathlib contributions or formalization projects.
• Ability to turn informal mathematics into correct formal statements and proofs.
• Strong background in proof-based mathematics or logic.
• Availability for at least 20 hours/week on weekdays.
• Clear written communication of proof strategy and formalization choices.

Responsibilities

• Write Lean 4 statements and proofs that compile against current mathlib across algebra, analysis, number theory, combinatorics and logic.
• Formalize natural-language mathematics, from problems to lemmas, ensuring fidelity to the original statement.
• Review AI-generated Lean statements and proofs, identifying gaps and providing precise feedback.
• Help define guidelines and rubrics for proof quality and mathlib conventions.
• Collaborate with Lean engineers and researchers to maintain high standards.

Skills

Lean 4 proofs

Formal mathematics

Proof strategy

Education

Degree in mathematics or logic

Tools

Lean 4

mathlib

Coq

Isabelle

Lean metaprogramming

Job description

Cincinnatus LLC is seeking Lean engineers and formal mathematicians to help its AI lab state and prove mathematics in Lean 4. You will write and review Lean proofs, formalize statements from informal math, and provide precise feedback on AI-generated proofs. Part-time commitment of 20–40 hours per week with potential to increase.

The role involves collaborating with researchers to ensure fidelity, contribute to proof quality guidelines, and work with mathlib across multiple areas of mathematics.