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GEOSTEER: Geodesic Optimization for Activation Steering in Large Language Models

arxiv.org/abs/2609.10658

Updated 15 min ago · first seen 11 Sept 2026

paper_01M294FNR3EX7ZFP8XA5MR6HEW

Published
11 Sept 2026
T1 · 15 min ago
arXiv
2609.10658
T1 · 15 min ago
Category
cs.LG
T1 · 15 min ago

Abstract

Activation steering provides a lightweight way to control large language models (LLMs) by modifying their hidden activations at inference time. Among these approaches, norm-preserving steering aims to change model behavior without altering the activation norm, reducing the risk of representation collapse and degradation. However, existing norm-preserving methods are limited by predefined steering trajectories and by their reliance on one-step updates, which may fail to capture the complex structure of activation distributions. We propose GeoSteer, an optimization-based method for norm-preserving activation steering. GeoSteer formulates steering as a Riemannian optimization problem and updates activations through a sequence of small geodesic steps on the representation manifold. To avoid fixed steering directions, GeoSteer learns a nonlinear activation-space objective that distinguishes desired from undesired activations, and uses this function to adaptively guide each steering step. This multistep formulation yields smoother, more stable, and more consistent steering behavior while preserving the activation norm. Across TruthfulQA, RealToxicityPrompts, and UltraFeedback benchmarks, GeoSteer consistently improves over state-of-the-art activation steering baselines. These results suggest that norm-preserving steering can be made more effective by replacing predefined one-step edits with adaptive, geometry-aware optimization.

Authors 3

Xuan Cuong Ngo, Hao Vo, Ngan Le

Specification

Official page

Source:arXiv (Atom API + RSS)T1observed 15 min agohigh

Arxiv announce type
new

Source:arXiv (Atom API + RSS)T1observed 15 min agohigh

arXiv id
2609.10658

Source:arXiv (Atom API + RSS)T1observed 15 min agohigh

Categories
cs.LG

Source:arXiv (Atom API + RSS)T1observed 15 min agohigh

PDF

Source:arXiv (Atom API + RSS)T1observed 15 min agohigh

Primary category
cs.LG

Source:arXiv (Atom API + RSS)T1observed 15 min agohigh

Published
11 Sept 2026

Source:arXiv (Atom API + RSS)T1observed 15 min agohigh

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Provenance

Attributed facts

9

Source tiers

T19

Freshest observation

15 min ago

Conflicts

None