PRISM: Efficient Long-Range Reasoning With Short-Context LLMs

Dulhan Jayalath, James Bradley Wendt, Nicholas Monath, Sandeep Tata, Beliz Gunel


Abstract
Long-range tasks demand reasoning over long inputs. However, existing solutions are limited, e.g., long-context models require large compute budgets, parameter-efficient fine-tuning (PEFT) needs training data, and retrieval-augmented generation (RAG) entails complex task-specific designs. Though in-context approaches overcome many of these issues, methods with short-context LLMs are inefficient, trading context for processing more tokens. We introduce **PRISM**, a highly token-efficient in-context method based on structured schemas that outperforms baselines on diverse tasks with **4x shorter contexts**. This approach produces concise outputs and efficiently leverages key-value (KV) caches to **reduce costs by up to 54%**. PRISM scales down to tiny contexts without increasing costs or sacrificing quality, and generalizes to new tasks with minimal effort by generating schemas from task descriptions.
Anthology ID:
2025.emnlp-main.517
Volume:
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
10207–10229
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URL:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.517/
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Cite (ACL):
Dulhan Jayalath, James Bradley Wendt, Nicholas Monath, Sandeep Tata, and Beliz Gunel. 2025. PRISM: Efficient Long-Range Reasoning With Short-Context LLMs. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing, pages 10207–10229, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
PRISM: Efficient Long-Range Reasoning With Short-Context LLMs (Jayalath et al., EMNLP 2025)
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https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.517.pdf
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