arXiv Machine Learning By Xuhan Tong, Yuchen Zeng, Jiawei Zhang

Out of Support, Not Out of Reach: In-Context Learning with Unsupported Instructions and Composed Tasks

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The paper investigates when in‑context learning (ICL) can succeed even if the instruction or target task is not covered by a model’s pretraining data. It introduces a theoretical framework that distinguishes two types of distribution shift—unsupported instructions and unsupported target tasks—and shows how demonstrations can mitigate these shifts. The authors further extend the analysis to long‑horizon tasks that can be decomposed into pretraining‑supported subtasks, providing error bounds that explain how ICL can handle tasks beyond the model’s original support.

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