Lean-STaR trains theorem provers to interleave informal thinking with Lean tactics

The method generates retrospective thoughts from known tactics and then uses expert iteration on newly discovered verified proofs.

What happened?

Lean-STaR improved miniF2F pass@64 from 43.4% to 46.3% by training models to generate synthetic informal thoughts before tactics.

Why it matters

It explored a direct bridge between chain-of-thought-style reasoning and proof-assistant feedback.

Significance rationale: Lean-STaR explicitly inserted learned informal thoughts before proof steps and combined them with expert iteration.

Historical context

Primary evidence

Evidence & status at a glance

Significance
H2 · Field milestone
Verification
Paper released
Evidence level
E2 · Research record
AI role
AI primary, human verified
Formal assurance
Machine-checked

How should these labels be read? →

Contribution & verification

Mathematical novelty
Benchmark result
Interface
Informal, Formal, Hybrid
AI contribution
The model generates both informal thoughts and Lean tactics, while Lean verifies the proof state.
Human contribution
Researchers designed synthetic-thought generation, expert iteration and evaluation.
Verification
Paper released · E2 · Research record · Machine-checked
Last reviewed
2026-09-11

Technical details

Systems
lean-star, lean
Organizations
carnegie-mellon-university
Problems
minif2f
Methods
expert-iteration, synthetic-thought, lean

Sources & artifacts

Verification history

  • 2024-07-14 · Paper released · E2 · Research record

    The Chronicle records this event from the cited primary or official source; the status does not imply independent Chronicle verification.

Corrections

No corrections recorded.