LEGO-Prover

Grows a persistent library of verified Isabelle/HOL helper lemmas while proving theorems block-by-block.

Read the paper

The loop

  1. Proposes

    A prover LLM decomposes a theorem into candidate helper lemmas and formal Isabelle proof sketches, while an evolvar LLM mutates verified lemmas in the skill library.

  2. Judged by

    The Isabelle/HOL kernel and Sledgehammer verify every proposed lemma and proof sketch.

  3. Steers

    Verified lemmas are indexed into a growing modular skill library and retrieved via semantic search to simplify subsequent theorems.

Headline result

Raised miniF2F-valid pass@100 to 57.0% and miniF2F-test to 50.0% in Isabelle/HOL, accumulating thousands of reusable verified lemmas.

What this does not prove

Library quality depends on pruning redundant or overly specialized lemmas so retrieval stays sharp.

How it generalizes the harness

The Isabelle/HOL kernel gates admission into a persistent, evolving library of formally verified mathematical lemmas.

Classification

Classification of LEGO-Prover
What it proposesProof
Generative modelGPT-3.5 / LLaMA-2 prover and lemma-evolver agents
Algorithmic authorityIsabelle/HOL proof kernel and Sledgehammer ATP
FeedbackProof state
What gets updatedPopulation of candidates and prompt context
When it runsAt inference time
ValidityFormal (machine-checked)
EvidenceCode released
LineageSuccessor