Not All Invariants Are Equal: Curating Training Data to Accelerate Program Verification with SLMs

Fuente: arXiv
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Autori principali: Pinto, Ido, Elboher, Yizhak Yisrael, Wu, Haoze, Narodytska, Nina, Katz, Guy
Natura: Preprint
Pubblicazione: 2026
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author Pinto, Ido
Elboher, Yizhak Yisrael
Wu, Haoze
Narodytska, Nina
Katz, Guy
author_facet Pinto, Ido
Elboher, Yizhak Yisrael
Wu, Haoze
Narodytska, Nina
Katz, Guy
contents The synthesis of inductive loop invariants is a critical bottleneck in automated program verification. While Large Language Models (LLMs) show promise in mitigating this issue, they often fail on hard instances, generating invariants that are invalid or computationally ineffective. While fine-tuning is a natural route to mitigate this limitation, obtaining high-quality training data for invariant generation remains an open challenge. We present a rigorous data curation pipeline designed to extract high-quality training signals from raw verifier-generated invariants. First, we formalize the properties required for a high-quality training invariant. Second, we propose Wonda, a pipeline that refines noisy data via AST-based normalization, followed by LLM-driven semantic rewriting and augmentation with provable quality guarantees. We demonstrate that fine-tuning Small Language Models (SLMs) on this curated dataset result in consistent and significant performance gain. In particular, a fine-tuned 4B parameter model matches the utility of a GPT-OSS-120B baseline and approaches the state-of-the-art GPT-5.2, without incurring reasoning-time overhead. On challenging instances from the recent InvBench evaluation suite, our approach doubles the invariant correctness and speedup rates of base models; and improves their Virtual Best Performance (VBP) rates on the verification task by up to 14.2%.
format Preprint
id arxiv_https___arxiv_org_abs_2603_15510
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Not All Invariants Are Equal: Curating Training Data to Accelerate Program Verification with SLMs
Pinto, Ido
Elboher, Yizhak Yisrael
Wu, Haoze
Narodytska, Nina
Katz, Guy
Machine Learning
68Q45
The synthesis of inductive loop invariants is a critical bottleneck in automated program verification. While Large Language Models (LLMs) show promise in mitigating this issue, they often fail on hard instances, generating invariants that are invalid or computationally ineffective. While fine-tuning is a natural route to mitigate this limitation, obtaining high-quality training data for invariant generation remains an open challenge. We present a rigorous data curation pipeline designed to extract high-quality training signals from raw verifier-generated invariants. First, we formalize the properties required for a high-quality training invariant. Second, we propose Wonda, a pipeline that refines noisy data via AST-based normalization, followed by LLM-driven semantic rewriting and augmentation with provable quality guarantees. We demonstrate that fine-tuning Small Language Models (SLMs) on this curated dataset result in consistent and significant performance gain. In particular, a fine-tuned 4B parameter model matches the utility of a GPT-OSS-120B baseline and approaches the state-of-the-art GPT-5.2, without incurring reasoning-time overhead. On challenging instances from the recent InvBench evaluation suite, our approach doubles the invariant correctness and speedup rates of base models; and improves their Virtual Best Performance (VBP) rates on the verification task by up to 14.2%.
title Not All Invariants Are Equal: Curating Training Data to Accelerate Program Verification with SLMs
topic Machine Learning
68Q45
url https://arxiv.org/abs/2603.15510