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Full-stack recurrence

LoopCD

Decoding Looped Transformers Better for (Almost) Free

Weihao Liu, Huangjie Zheng, Tianrong Chen, Rohit Dilip, Richard He Bai, Yizhu Jiao, Yuyang Wang, Ruixiang Zhang

Training-free contrastive decoding that contrasts a looped model's final prediction with an earlier recurrent pass, which serves as a built-in weak model. It works in logit space with one extra output pass or in hidden-state space with no extra output cost.

Inside the method

Final-loop prediction − λ · earlier-loop prediction → token

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

Recurrence family
Full-stack recurrence
Depth control
Full depth, or about half the loops with guidance
KV / state strategy
See paper

Reading note

Raises Ouro-2.6B-Thinking's AIME 2024 pass@1 from 61.88% to 73.33% and Huginn's HumanEval pass@1 from 22.56% to 31.71%. With guidance, halving the loops matches or beats unguided full depth, saving 22.5–48.2% forward FLOPs.

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

Related works

Cite this work

@misc{loopcd2026,
  title = {Decoding Looped Transformers Better for (Almost) Free},
  author = {Weihao Liu and Huangjie Zheng and Tianrong Chen and Rohit Dilip and Richard He Bai and Yizhu Jiao and Yuyang Wang and Ruixiang Zhang},
  year = {2026},
  eprint = {2610.02185},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.02185}
}

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