Memorize Theorems, Not Instances: Probing SFT Generalization through Mathematical Reasoning

Fuente: arXiv
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Main Authors: Peng, Ruiying, Yang, Mengyu, Lei, Jing, Li, Xiaohui, Wu, Xueyu, Chen, Xinlei
Format: Preprint
Published: 2026
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_version_ 1866914598715654144
author Peng, Ruiying
Yang, Mengyu
Lei, Jing
Li, Xiaohui
Wu, Xueyu
Chen, Xinlei
author_facet Peng, Ruiying
Yang, Mengyu
Lei, Jing
Li, Xiaohui
Wu, Xueyu
Chen, Xinlei
contents Supervised Fine-Tuning (SFT) is widely used for task-specific adaptation, yet recent work shows it systematically undermines reasoning generalization. We argue the root cause is not memorization itself, but its target: vanilla SFT drives models to exploit and memorize spurious surface correlations in problem-solution pairs, leaving them brittle to superficial input variations. To address this, we propose Theorem-SFT, which reorients supervision toward explicit theorem application by teaching models how rules are invoked rather than what answers look like. Theorem-SFT yields consistent gains across benchmarks and model families: +8.8% on MATH (LLaMA3.2-3B-Instruct) and +20.27% on GeoQA (Qwen2.5-VL-7B-Instruct) without modality-specific re-training. Fine-tuning MLP layers alone matches full-layers performance, implicating feed-forward components as the primary locus of reasoning rules. Our findings reframe the debate: Generalization failures stem not from memorization as a mechanism, but from memorizing the wrong inductive targets.
format Preprint
id arxiv_https___arxiv_org_abs_2605_09270
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Memorize Theorems, Not Instances: Probing SFT Generalization through Mathematical Reasoning
Peng, Ruiying
Yang, Mengyu
Lei, Jing
Li, Xiaohui
Wu, Xueyu
Chen, Xinlei
Machine Learning
Artificial Intelligence
Supervised Fine-Tuning (SFT) is widely used for task-specific adaptation, yet recent work shows it systematically undermines reasoning generalization. We argue the root cause is not memorization itself, but its target: vanilla SFT drives models to exploit and memorize spurious surface correlations in problem-solution pairs, leaving them brittle to superficial input variations. To address this, we propose Theorem-SFT, which reorients supervision toward explicit theorem application by teaching models how rules are invoked rather than what answers look like. Theorem-SFT yields consistent gains across benchmarks and model families: +8.8% on MATH (LLaMA3.2-3B-Instruct) and +20.27% on GeoQA (Qwen2.5-VL-7B-Instruct) without modality-specific re-training. Fine-tuning MLP layers alone matches full-layers performance, implicating feed-forward components as the primary locus of reasoning rules. Our findings reframe the debate: Generalization failures stem not from memorization as a mechanism, but from memorizing the wrong inductive targets.
title Memorize Theorems, Not Instances: Probing SFT Generalization through Mathematical Reasoning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2605.09270