Reasoning Cache: Continual Improvement Over Long Horizons via Short-Horizon RL

Fuente: arXiv
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Autori principali: Wu, Ian, Qu, Yuxiao, Setlur, Amrith, Kumar, Aviral
Natura: Preprint
Pubblicazione: 2026
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author Wu, Ian
Qu, Yuxiao
Setlur, Amrith
Kumar, Aviral
author_facet Wu, Ian
Qu, Yuxiao
Setlur, Amrith
Kumar, Aviral
contents Large Language Models (LLMs) that can continually improve beyond their training budgets are able to solve increasingly difficult problems by adapting at test time, a property we refer to as extrapolation. However, standard reinforcement learning (RL) operates over fixed problem distributions and training budgets, which limits extrapolation amidst distribution shift at test time. To address this, we introduce RC, an iterative decoding algorithm that replaces standard autoregressive decoding during both training and inference. RC exploits an asymmetry between the response generation and summarization capabilities of LLMs to construct reasoning chains that consistently improve across iterations. Models trained to use RC can extrapolate and continually improve over reasoning horizons more than an order of magnitude longer than those seen during training. Empirically, training a 4B model with RC using a 16k-token training budget improves performance on HMMT 2025 from 40% to nearly 70% with 0.5m tokens at test time, outperforming both comparably sized models and many larger reasoning LLMs. Finally, we also show that models trained with RC can more effectively leverage existing scaffolds to further scale test-time performance, due to the improved summary-conditioned generation abilities learned through training.
format Preprint
id arxiv_https___arxiv_org_abs_2602_03773
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Reasoning Cache: Continual Improvement Over Long Horizons via Short-Horizon RL
Wu, Ian
Qu, Yuxiao
Setlur, Amrith
Kumar, Aviral
Machine Learning
Large Language Models (LLMs) that can continually improve beyond their training budgets are able to solve increasingly difficult problems by adapting at test time, a property we refer to as extrapolation. However, standard reinforcement learning (RL) operates over fixed problem distributions and training budgets, which limits extrapolation amidst distribution shift at test time. To address this, we introduce RC, an iterative decoding algorithm that replaces standard autoregressive decoding during both training and inference. RC exploits an asymmetry between the response generation and summarization capabilities of LLMs to construct reasoning chains that consistently improve across iterations. Models trained to use RC can extrapolate and continually improve over reasoning horizons more than an order of magnitude longer than those seen during training. Empirically, training a 4B model with RC using a 16k-token training budget improves performance on HMMT 2025 from 40% to nearly 70% with 0.5m tokens at test time, outperforming both comparably sized models and many larger reasoning LLMs. Finally, we also show that models trained with RC can more effectively leverage existing scaffolds to further scale test-time performance, due to the improved summary-conditioned generation abilities learned through training.
title Reasoning Cache: Continual Improvement Over Long Horizons via Short-Horizon RL
topic Machine Learning
url https://arxiv.org/abs/2602.03773