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Main Authors: Li, Tianchi, Yan, Zhenyu, Liu, Junhao, Di, Peng, Zhang, Xin
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.17914
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author Li, Tianchi
Yan, Zhenyu
Liu, Junhao
Di, Peng
Zhang, Xin
author_facet Li, Tianchi
Yan, Zhenyu
Liu, Junhao
Di, Peng
Zhang, Xin
contents We propose a novel framework that provides constructive feedback to an LLM in the "guess-and-check" paradigm by formally verifying its own thinking process and detecting local reasoning errors. We apply this framework to the loop invariant synthesis problem. We prompt the model to produce a step-by-step natural language proof justifying its thinking process for the failed verification condition of its generated loop invariants. Then, we use an LLM to translate the reasoning steps into first-order logic implications, which can be checked automatically. An invalid implication pinpoints the exact logical flaw in the LLM's thinking process, which we then use to construct targeted feedback for refinement. We have implemented our approach in a tool called LORIS and evaluated it on a main benchmark suite of 460 C programs and an additional benchmark suite of 50 C programs each of which involves non-linear properties. On the main benchmark suite, LORIS solved 445 of the programs, and achieved an overall success rate of $93.1\%$. LORIS also demonstrates robustness on the challenging non-linear benchmark suite.
format Preprint
id arxiv_https___arxiv_org_abs_2605_17914
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Guiding LLM-based Loop Invariant Synthesis via Feedback on Local Reasoning Errors
Li, Tianchi
Yan, Zhenyu
Liu, Junhao
Di, Peng
Zhang, Xin
Programming Languages
We propose a novel framework that provides constructive feedback to an LLM in the "guess-and-check" paradigm by formally verifying its own thinking process and detecting local reasoning errors. We apply this framework to the loop invariant synthesis problem. We prompt the model to produce a step-by-step natural language proof justifying its thinking process for the failed verification condition of its generated loop invariants. Then, we use an LLM to translate the reasoning steps into first-order logic implications, which can be checked automatically. An invalid implication pinpoints the exact logical flaw in the LLM's thinking process, which we then use to construct targeted feedback for refinement. We have implemented our approach in a tool called LORIS and evaluated it on a main benchmark suite of 460 C programs and an additional benchmark suite of 50 C programs each of which involves non-linear properties. On the main benchmark suite, LORIS solved 445 of the programs, and achieved an overall success rate of $93.1\%$. LORIS also demonstrates robustness on the challenging non-linear benchmark suite.
title Guiding LLM-based Loop Invariant Synthesis via Feedback on Local Reasoning Errors
topic Programming Languages
url https://arxiv.org/abs/2605.17914