Riemannian Optimization for LoRA on the Stiefel Manifold
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Abstract (arXiv)
While powerful, large language models (LLMs) present significant fine-tuning challenges due to their size. Parameter-efficient fine-tuning (PEFT) methods like LoRA provide solutions, yet suffer from critical optimizer inefficiencies; notably basis redundancy in LoRA's B matrix when using AdamW, which fundamentally limits performance. We address this by optimizing the B matrix on the Stiefel manifold, imposing explicit orthogonality constraints that achieve near-perfect orthogonality and full effective rank. This geometric approach dramatically enhances parameter efficiency and representational capacity. Our Stiefel optimizer consistently outperforms AdamW across benchmarks with both LoRA and DoRA, demonstrating that geometric constraints are the key to unlocking LoRA's full potential for effective LLM fine-tuning.
Key facts. Cited by 10 papers in the map (data through 14 Oct 2026). Builds on 25 of its 40 references that are in the map. First posted on arXiv 25 Aug 2025.
Builds on
25 of 40 references.
References · 25
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13 more
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Built on by
Citing papers per year: 2025: 1; 2026: 9.
10 papers.
- 2026Mano: Restriking Manifold Optimization for LLM Trainingcited by 12
- 2026Intrinsic Muon: Spectral Optimization on Riemannian Matrix Manifoldscited by 6
- 2026Balanced LoRA: Removing Parameter Invariance to Accelerate Convergencecited by 3
- 2025Timber: Training-free Instruct Model Refining with Base via Effective Rankcited by 2
- 2026FoRA: Fisher-orthogonal Rank Adaptation for Parameter-Efficient Fine-Tuningcited by 1
- 2026Calibrated Adaptation: Bayesian Stiefel Manifold Priors for Reliable Parameter-Efficient Fine-Tuningcited by 0
- 2026Riemannian Stochastic Optimization for Sufficient Dimension Reductioncited by 0
- 2026When Top-1 Fails: Calibrating LoRA Monitors for Masked Diffusion LMscited by 0
- 2026Retraction-Free Optimization over the Stiefel Manifold for the LoRA Fine-Tuningcited by 0
- 2026Geometry-Aware Bayesian Parameter-Efficient Fine-Tuning on the Stiefel Manifold via Stein Variational Gradient Descentcited by 0
- 2026Geometry-Aware Bayesian Parameter-Efficient Fine-Tuning on the Stiefel Manifold via Stein Variational Gradient Descent8 Sep 2026
- 2026Retraction-Free Optimization over the Stiefel Manifold for the LoRA Fine-Tuning28 Jul 2026
- 2026When Top-1 Fails: Calibrating LoRA Monitors for Masked Diffusion LMs23 Jun 2026
- 2026Riemannian Stochastic Optimization for Sufficient Dimension Reduction29 May 2026
- 2026Balanced LoRA: Removing Parameter Invariance to Accelerate Convergence29 May 2026
- 2026FoRA: Fisher-orthogonal Rank Adaptation for Parameter-Efficient Fine-Tuning28 May 2026
- 2026Intrinsic Muon: Spectral Optimization on Riemannian Matrix Manifolds10 May 2026
- 2026Calibrated Adaptation: Bayesian Stiefel Manifold Priors for Reliable Parameter-Efficient Fine-Tuning19 Feb 2026
- 2026Mano: Restriking Manifold Optimization for LLM Training30 Jan 2026
- 2025Timber: Training-free Instruct Model Refining with Base via Effective Rank28 Sep 2025