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Core recurrence

Quantizing Looped Transformers

Quantizing Looped Transformers: Feedback Exposure and Calibration Blindness

Nux Li

Identifies two failure modes of post-training quantization in looped models: feedback exposure, where a quantized non-residual layer such as the loop-entry adapter perturbs the state and the error is fed back, and calibration blindness, where one-step calibration ignores directions used later in the recurrence.

Inside the method

Prelude → adapter → [ Core ] × R → Coda (where quantization error enters)

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

Recurrence family
Core recurrence
Depth control
Fixed recurrence
KV / state strategy
See paper

Reading note

On Huginn-3.5B, INT4 fails mainly at the loop-entry adapter. Across nine checkpoints from seven looped architectures, accumulating the GPTQ Hessian across recurrence steps beats one-step GPTQ and RTN everywhere and recovers bf16-level accuracy on Huginn.

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

Related works

Cite this work

@misc{quantizingloopedtransformers2026,
  title = {Quantizing Looped Transformers: Feedback Exposure and Calibration Blindness},
  author = {Nux Li},
  year = {2026},
  eprint = {2609.30820},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.30820}
}

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