Original title: LoRA-TSD: Tangent-Space Spectral Descent for LoRA via Muon-Style Updates
Dmitrii Andriianov, Andrey Veprikov, Aleksandr Beznosikov · September 2026
Tuning large artificial intelligence models usually relies on a method called LoRAA method to fine-tune large models by updating two low-rank matrices instead of all parameters.. LoRA updates weights by splitting them into two smaller parts called factors. Training these two parts independently causes an issue: it ignores the true mathematical shape of the full update. To solve this, researchers built an optimizer called LoRA-TSD. It treats each update step as a direction along a curved mathematical surface of low-rank matrices. It takes a specialized steep step inspired by an algorithm called Muon within that space. Then, it maps the update back into the two factors using a custom shortcut. This shortcut avoids heavy full-matrix calculations. In tests across six benchmarks, LoRA-TSD beat every competing LoRA optimizer and stayed reliable regardless of the chosen adapter rank.
Imagine you are tuning a musical instrument, like a guitar. If you adjust each string independently, they might not harmonize well because the tension affects the whole instrument. Here, the system considers how adjusting one string changes the overall tension and tunes them together to maintain harmony. In this paper, LoRA-TSD does this for model parameters, respecting how updates interact to improve fine-tuning.
For anyone fine-tuning large AI models, this optimizer makes the process more effective and cheaper. It outperforms current methods across standard benchmarks, which could lead to better model performance with less computational effort.
The abstract doesn't state explicit limitations, but the work is tested only on specific benchmarks and models. It may not apply to all types of fine-tuning or different model architectures. Also, the convergence guarantees are under theoretical conditions that might not hold in all practical cases.
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LoRA-TSD: Tangent-Space Spectral Descent for LoRA via Muon-Style Updates — Dmitrii Andriianov, Andrey Veprikov, Aleksandr Beznosikov
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.