Towards Looped Models Done Right: sandwich architecture improves reasoning, transfers to MoE

IFM · hf · 2026-10-19

A team from IFM, USC, and CMU (including Eric Xing) releases part one of a systematic study on looped language models. Established architectures entangle three design axes—recurrence placement, input injection, and recurrent-state organization. The authors train models from scratch at matched parameter scale, logical depth, and token budgets to isolate each axis.

Key findings: a prelude–recurrent block–coda sandwich architecture consistently improves context extraction and reasoning-intensive tasks; input injection primarily enhances knowledge retrieval and context utilization; and the design principles transfer to resident- and active-parameter-matched Mixture-of-Experts models. Code: github.com/ifm-ai/xllm-loop.

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