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The Proof Model Reads the Compiler's Rejection

A bounded repair loop fixes failed Lean tactics in place and gains most of its benefit on the first retry.

Published Updated Story ID: mp-2026-10-21-007
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Summary

A bounded repair loop fixes failed Lean tactics in place and gains most of its benefit on the first retry.

Sampling-only theorem provers throw away precise information when Lean rejects a tactic. This repair module returns the compiler error to a pretrained model and permits a bounded number of fixes. Across tested candidate budgets, it solved 82 additional theorems on a 1,990-theorem LeanDojo subset, with the first repair capturing 84 to 96 percent of the total gain. Benefits concentrated in shallow execution failures, not structural type errors, and replicated on Lean Workbook.

Why it matters

A bounded repair loop fixes failed Lean tactics in place and gains most of its benefit on the first retry.

Limits and context

  • Sampling-only theorem provers throw away precise information when Lean rejects a tactic.
  • Benefits concentrated in shallow execution failures, not structural type errors, and replicated on Lean Workbook.

Key claims

  1. A bounded repair loop fixes failed Lean tactics in place and gains most of its benefit on the first retry.

    Qualification: Sampling-only theorem provers throw away precise information when Lean rejects a tactic.

    Evidence: source-2026-10-21-007

Sources

  1. arXiv preprint 2610.26942, original v1arXiv · primary research

Corrections

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