Enhancing Small LLM Alignment through Margin-Based Objective Modifications under Resource Constraints

Fuente: arXiv
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Main Authors: Yao, Daren, Yuan, Jinsong, Chen, Ruike
Format: Preprint
Published: 2025
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author Yao, Daren
Yuan, Jinsong
Chen, Ruike
author_facet Yao, Daren
Yuan, Jinsong
Chen, Ruike
contents Small large language models (LLMs) often face difficulties in aligning output to human preferences, particularly when operating under severe performance gaps. In this work, we propose two lightweight DPO-based variants -- Adaptive Margin-Sigmoid Loss and APO-hinge-zero -- to better address underperformance scenarios by introducing margin-based objectives and selective update mechanisms. Our APO-hinge-zero method, which combines hinge-induced hard-example mining with the chosen-focused optimization of APO-zero, achieves strong results. In AlpacaEval, APO-hinge-zero improves the win rate by +2.0 points and the length-controlled win rate by +1.4 points compared to the APO-zero baseline. In MT-Bench, our methods maintain competitive performance in diverse categories, particularly excelling in STEM and Humanities tasks. These results demonstrate that simple modifications to preference-based objectives can significantly enhance small LLM alignment under resource constraints, offering a practical path toward more efficient deployment.
format Preprint
id arxiv_https___arxiv_org_abs_2508_08466
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Enhancing Small LLM Alignment through Margin-Based Objective Modifications under Resource Constraints
Yao, Daren
Yuan, Jinsong
Chen, Ruike
Computation and Language
Small large language models (LLMs) often face difficulties in aligning output to human preferences, particularly when operating under severe performance gaps. In this work, we propose two lightweight DPO-based variants -- Adaptive Margin-Sigmoid Loss and APO-hinge-zero -- to better address underperformance scenarios by introducing margin-based objectives and selective update mechanisms. Our APO-hinge-zero method, which combines hinge-induced hard-example mining with the chosen-focused optimization of APO-zero, achieves strong results. In AlpacaEval, APO-hinge-zero improves the win rate by +2.0 points and the length-controlled win rate by +1.4 points compared to the APO-zero baseline. In MT-Bench, our methods maintain competitive performance in diverse categories, particularly excelling in STEM and Humanities tasks. These results demonstrate that simple modifications to preference-based objectives can significantly enhance small LLM alignment under resource constraints, offering a practical path toward more efficient deployment.
title Enhancing Small LLM Alignment through Margin-Based Objective Modifications under Resource Constraints
topic Computation and Language
url https://arxiv.org/abs/2508.08466