arXiv AI By Zirong Xie, Zainab Afolabi, Nikita Kozodoi, Jack Butler

Model Merging Does Not Require Uniform LoRA Ranks

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The paper investigates whether model merging requires all experts to use the same LoRA rank. Experiments with 36 experts across three domains and multiple ranks show that allowing each expert its own optimal rank improves multi‑domain accuracy by up to 1.8 percentage points, while traditional uniform‑rank methods can even degrade performance. The authors attribute this to how merge methods select spectral components, arguing that rank can be chosen per expert when the merge operator does not rely on magnitude alone.

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