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SAMoRA: Semantic-Aware Mixture of LoRA Experts for Task-Adaptive Learning

Paper · 2026 · Boyan Shi, Wei Chen, Shuyuan Zhao et al.

Summary

Combining Mixture-of-Experts with LoRA (MoE-LoRA) is a common way to fine-tune LLMs on many tasks at once. The authors identify two weaknesses in this approach. First, MLP routers assign inputs to experts without explicitly considering what each expert is good at, so the experts tend to become alike. Second, a single fixed LoRA scaling factor applies the same update strength to easy and hard tasks.

SAMoRA addresses both problems. It uses an asymmetric design, borrowed from HydraLoRA, with one shared matrix A and several specialized B experts. The shared A doubles as a semantic encoder whose output is compared against learned expert keys to make routing decisions. A Task-Adaptive Scaling module turns task embeddings into sigmoid-bounded diagonal scaling factors. Two auxiliary losses, one for orthogonality and one for semantic matching, push experts toward distinct roles.

On Commonsense Reasoning and GLUE with 8B-scale models, SAMoRA outperforms several LoRA-family baselines while training fewer parameters. This makes it a practical option for efficient multi-task adaptation.

Key points

  • Baselines: LoRA, MultiLoRA, MTL-LoRA, MoELoRA, HydraLoRA and MoORE. The authors attribute MoORE's weak results to its small trainable budget, since it trains only the router.
  • Ablation on CoLA: Removing task-adaptive scaling causes the largest drop, from 69.75% to 66.43%. Removing the semantic router, L_orth or L_match also lowers scores.
  • Expert specialization: PCA plots on Commonsense Reasoning show clearly separated clusters for 8 experts under SAMoRA. The MLP router produces entangled clusters.
  • Scaling behavior: On Qwen3-8B, the learned scaling factors for the q/k/v/o projections differ across tasks. Sensitivity tests (N, r, d_g, λ_orth, λ_KL, τ) indicate the method is robust and that small task embeddings are sufficient.
  • Limitations and code: The method has not been tested on models of 70B or larger, nor in multimodal settings. Code is available at github.com/boyan-code/SAMoRA.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

Also on the byline: Guilin University of Electronic Technology.

 Fields, topics and concepts

Cite

Cite as Boyan Shi, Wei Chen, Shuyuan Zhao, Junfeng Shen, Shengnan Guo, Shaojiang Wang and Huaiyu Wan. 2026. SAMoRA: Semantic-Aware Mixture of LoRA Experts for Task-Adaptive Learning. Findings of the Association for Computational Linguistics: ACL 2026.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.findings-acl.1404

@inproceedings{shi2026samora,
  title = {{SAMoRA: Semantic-Aware Mixture of LoRA Experts for Task-Adaptive Learning}},
  author = {Boyan Shi, Wei Chen, Shuyuan Zhao, Junfeng Shen, Shengnan Guo, Shaojiang Wang and Huaiyu Wan},
  booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
  year = {2026},
  doi = {10.18653/v1/2026.findings-acl.1404},
  url = {https://doi.org/10.18653/v1/2026.findings-acl.1404}
}

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