arXiv AI

Rank-Aware Differentially Private Release of Listwise Preferences for LLM Alignment

The paper introduces a rank‑aware exponential mechanism that privatizes listwise preference data for large language model alignment under local differential privacy. By sampling a fixed‑size binary partition, the method concentrates noise near borderline items rather than uniformly across all items, thereby reducing sensitivity. Experiments demonstrate that this approach outperforms existing LDP baselines on downstream alignment tasks while maintaining the same privacy budget.

arXiv AI
Jun 16

SDFLoRA: Selective Decoupled Federated LoRA for Privacy-preserving Fine-tuning with Heterogeneous Clients

arXiv:2601. 11219v3 Announce Type: replace-cross Abstract: Federated learning (FL) for large language models (LLMs) has attracted increasing attention as a privacy-preserving approach for adapting models over distributed data, where parameter-efficient methods such as Low-Rank Adaptation (LoRA) are widely adopted to reduce communication and memory costs.

By Zhikang Shen, Jianrong Lu, Haiyuan Wan, Jianhai Chen
arXiv AI
Oct 9

Nullify: Null-Space Activation Steering for Training-Free LLM Unlearning

Nullify is a training‑free method for unlearning sensitive information from large language models by steering activations during inference. It uses steering vectors to redirect privacy‑related activations away from memorized answers while enforcing a null‑space constraint that preserves activations for retained queries, thereby maintaining model utility. Experiments on TOFU and MUSE demonstrate that Nullify matches or outperforms existing baselines in forget quality while keeping utility nearly intact, all without any weight updates.

By Wei Zhai, Xiang Liu, Qiang Huang, Rui Qian, Lemao Liu, Ziwei Li, Ziqi Wang, Zhitao Huang, Dejing Dou
arXiv AI
Sep 2

Breaking the Structural Identity: Personalized Federated LoRA Fine-tuning under Rank Heterogeneity

The paper introduces FedRoRA, a federated learning framework that combines Low‑Rank Adaptation (LoRA) with rank‑heterogeneous personalization. It separates model adaptation into shared global directions and client‑specific rank‑wise magnitudes, using SVD on the server to extract a global subspace and a personalized projection with top‑k selection for each client. Experiments on natural language understanding and generation tasks show that FedRoRA outperforms existing state‑of‑the‑art methods.

By Lei Wang, Jieming Bian, Letian Zhang, Jie Xu
arXiv Machine Learning
Oct 22

Differentially Private Sparse Reward Estimation with Preference Feedback

The paper introduces a differentially private framework for sparse reward estimation in reinforcement learning with human feedback (RLHF). It assumes that only a small subset of features influences human preferences and provides theoretical error bounds for both Sample-DP and Label-DP settings under the Bradley-Terry-Luce model. Empirical results show that the proposed methods outperform dense baselines on sentiment generation and safety alignment tasks, achieving a better privacy‑utility trade‑off.

By Meng Ding, Mingxi Lei, Jie Zhang, Jinyan Liu, Di Wang