Suan: Gradient Preference Optimization against Over-Refusals in Open LLMs

9 October 20262 views

The authors propose the Suan algorithm, which sets the training objective directly at the gradient level, bypassing standard variational inference, yielding more predictable and interpretable training dynamics. Based on tests on a set of benchmarks, the method provides enhanced protection without the loss of response usefulness typical of open models.

Suan: Gradient Preference Optimization against Over-Refusals in Open LLMs

Security Challenge in Open Models

Embedding robust safeguards into large language models is essential for helpful and harmless responses.

  • Proprietary systems demonstrate robust safety control.
  • Their methods and trade-offs remain largely undisclosed.
  • Achieving comparable safety in open models remains a persistent challenge.
  • Post-trained variants often suffer from excessive refusals and a drop in overall quality.

Suan is a new preference optimization algorithm. It was created to overcome these shortcomings. Practical criterion: if an open model refuses too often and loses quality, a method is needed that corrects safety alignment without sacrificing helpfulness.

Direct Gradient Optimization

Suan formulates the optimization objective directly at the gradient level. This approach bypasses standard variational inference. As a result, training becomes more interpretable and stable.

AspectWhat Suan changes relative to the standard approach
Objective formulationDirect gradient level instead of standard variational inference
Training dynamicsMore interpretable and stable

The selection criterion is to look at where the objective is formulated. The direct gradient level yields more transparent training dynamics.

Evaluation and Results

Suan underwent extensive evaluations. They cover a diverse set of competitive baselines and benchmarks.

  • The algorithm achieves excellent safety alignment.
  • The algorithm fully preserves response helpfulness.

Practical criterion: compare safety and helpfulness together. Evaluating only refusals does not show overall quality. Evaluating only quality does not show protection.

Output Data

The paper is titled "Suan: Rectifying Direct Preference Safety Alignment in Large Language Models."

  • Authors — Oleksandr Cherednichenko, Roman Klypa.
  • arXiv:2609.08634 (cs).
  • Submission date — September 8, 2026.
  • Subjects: Machine Learning (cs.LG); Artificial Intelligence (cs.AI).
  • DOI: https://doi.org/10.48550/arXiv.2609.08634 (pending registration).
  • Submission history: from Oleksandr Cherednichenko; [v1] Tue, 8 Sep 2026 12:04:38 UTC (426 KB).
  • Cite as arXiv:2609.08634 [cs.LG] (or arXiv:2609.08634v1 [cs.LG] for this version).

Practical criterion: use the arXiv ID and DOI for citation. The DOI is currently pending registration.

Frequently asked questions

Suan: Gradient Preference Optimization against Over-Refusals in Open LLMs