Moogle

Moogle is a specialized semantic search tool for mathlib4, the theorem library for Lean 4. It helps mathematicians, researchers, and formal methods developers find the right theorems and lemmas faster.

Semantic theorem search

Unlike basic keyword search, Moogle accounts for mathematical meaning and query structure. You can phrase queries more naturally and still get relevant matches even when mathlib4 states a theorem differently than you would.

Built for Lean 4 and mathlib4 workflows

Moogle is especially useful when navigating the large mathlib4 codebase and reusing existing results.

• Find suitable facts and lemmas more quickly
• Reduce time spent searching through the library manually
• Support learning and onboarding for new Lean users
• Improve productivity when formalizing mathematics and writing proofs