SplitReason: Learning To Offload Reasoning

Fuente: arXiv
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Main Authors: Akhauri, Yash, Fei, Anthony, Chang, Chi-Chih, AbouElhamayed, Ahmed F., Li, Yueying, Abdelfattah, Mohamed S.
Format: Preprint
Published: 2025
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author Akhauri, Yash
Fei, Anthony
Chang, Chi-Chih
AbouElhamayed, Ahmed F.
Li, Yueying
Abdelfattah, Mohamed S.
author_facet Akhauri, Yash
Fei, Anthony
Chang, Chi-Chih
AbouElhamayed, Ahmed F.
Li, Yueying
Abdelfattah, Mohamed S.
contents Reasoning in large language models (LLMs) tends to produce substantially longer token generation sequences than simpler language modeling tasks. This extended generation length reflects the multi-step, compositional nature of reasoning and is often correlated with higher solution accuracy. From an efficiency perspective, longer token generation exacerbates the inherently sequential and memory-bound decoding phase of LLMs. However, not all parts of this expensive reasoning process are equally difficult to generate. We leverage this observation by offloading only the most challenging parts of the reasoning process to a larger, more capable model, while performing most of the generation with a smaller, more efficient model; furthermore, we teach the smaller model to identify these difficult segments and independently trigger offloading when needed. To enable this behavior, we annotate difficult segments across 18k reasoning traces from the OpenR1-Math-220k chain-of-thought (CoT) dataset. We then apply supervised fine-tuning (SFT) and reinforcement learning fine-tuning (RLFT) to a 1.5B-parameter reasoning model, training it to learn to offload the most challenging parts of its own reasoning process to a larger model. This approach improves AIME24 reasoning accuracy by 24% and 28.3% while offloading 1.35% and 5% of the generated tokens respectively. We open-source our SplitReason model, data, code and logs.
format Preprint
id arxiv_https___arxiv_org_abs_2504_16379
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SplitReason: Learning To Offload Reasoning
Akhauri, Yash
Fei, Anthony
Chang, Chi-Chih
AbouElhamayed, Ahmed F.
Li, Yueying
Abdelfattah, Mohamed S.
Computation and Language
Reasoning in large language models (LLMs) tends to produce substantially longer token generation sequences than simpler language modeling tasks. This extended generation length reflects the multi-step, compositional nature of reasoning and is often correlated with higher solution accuracy. From an efficiency perspective, longer token generation exacerbates the inherently sequential and memory-bound decoding phase of LLMs. However, not all parts of this expensive reasoning process are equally difficult to generate. We leverage this observation by offloading only the most challenging parts of the reasoning process to a larger, more capable model, while performing most of the generation with a smaller, more efficient model; furthermore, we teach the smaller model to identify these difficult segments and independently trigger offloading when needed. To enable this behavior, we annotate difficult segments across 18k reasoning traces from the OpenR1-Math-220k chain-of-thought (CoT) dataset. We then apply supervised fine-tuning (SFT) and reinforcement learning fine-tuning (RLFT) to a 1.5B-parameter reasoning model, training it to learn to offload the most challenging parts of its own reasoning process to a larger model. This approach improves AIME24 reasoning accuracy by 24% and 28.3% while offloading 1.35% and 5% of the generated tokens respectively. We open-source our SplitReason model, data, code and logs.
title SplitReason: Learning To Offload Reasoning
topic Computation and Language
url https://arxiv.org/abs/2504.16379