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Adaptive depth

Accordion

Accordion: Elastic-Depth Inference via Fixed-Prefix Layer Looping

Yudong Zhang, Wei Ding, Kaili Zheng, Yuchen Ding, Zhenyu Zhang

A mixture-of-experts model that serves five inference budgets through fixed-prefix layer looping, with the smallest budget equal to the unlooped model. Pretraining samples one budget per micro-batch, and SFT and RL with budget-matched multi-teacher distillation preserve every budget.

Inside the method

Unlooped path → fixed-prefix layer looping for budgets 1…5

Simplified conceptual schematic. Consult the paper for the complete architecture.

Recurrence family
Adaptive depth
Depth control
Five predefined execution paths chosen at inference
KV / state strategy
See paper

Reading note

After 3.6T pretraining tokens, the deepest budget raises Accordion-6B-A0.5B's macro-average over 37 tasks by 3.01 points; the middle budget captures 89% of the gain with half the extra layer executions.

Sources checked 2026-10-28. This catalog does not imply independent reproduction.

Related works

Cite this work

@misc{accordion2026,
  title = {Accordion: Elastic-Depth Inference via Fixed-Prefix Layer Looping},
  author = {Yudong Zhang and Wei Ding and Kaili Zheng and Yuchen Ding and Zhenyu Zhang},
  year = {2026},
  eprint = {2610.32492},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.32492}
}

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