Reinforcement Learning for Compositional Generalization with Outcome-Level Optimization

Fuente: arXiv
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Auteurs principaux: Fu, Xiyan, Liu, Wei
Format: Preprint
Publié: 2026
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author Fu, Xiyan
Liu, Wei
author_facet Fu, Xiyan
Liu, Wei
contents Compositional generalization refers to correctly interpret novel combinations of known primitives, which remains a major challenge. Existing approaches often rely on supervised fine-tuning, which encourages models to imitate target outputs. This token-level training paradigm fails to capture the global compositional structure required for generalizing to unseen combinations. In this work, we investigate whether compositional generalization can instead be improved through outcome-level reinforcement learning. We adopt Group Relative Policy Optimization to optimize models based on feedback on their final outputs. Within this framework, we explore both a simple binary outcome reward and a composite reward that provides additional composition feedback. Experiments on multiple compositional benchmarks show that reinforcement learning improves compositional generalization compared to supervised fine-tuning. Further analysis reveals that supervised models tend to overfit frequent training compositions, whereas reinforcement learning improves compositional generalization by reshaping the output distribution, particularly for more complex composition types.
format Preprint
id arxiv_https___arxiv_org_abs_2605_04920
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Reinforcement Learning for Compositional Generalization with Outcome-Level Optimization
Fu, Xiyan
Liu, Wei
Machine Learning
Computation and Language
Compositional generalization refers to correctly interpret novel combinations of known primitives, which remains a major challenge. Existing approaches often rely on supervised fine-tuning, which encourages models to imitate target outputs. This token-level training paradigm fails to capture the global compositional structure required for generalizing to unseen combinations. In this work, we investigate whether compositional generalization can instead be improved through outcome-level reinforcement learning. We adopt Group Relative Policy Optimization to optimize models based on feedback on their final outputs. Within this framework, we explore both a simple binary outcome reward and a composite reward that provides additional composition feedback. Experiments on multiple compositional benchmarks show that reinforcement learning improves compositional generalization compared to supervised fine-tuning. Further analysis reveals that supervised models tend to overfit frequent training compositions, whereas reinforcement learning improves compositional generalization by reshaping the output distribution, particularly for more complex composition types.
title Reinforcement Learning for Compositional Generalization with Outcome-Level Optimization
topic Machine Learning
Computation and Language
url https://arxiv.org/abs/2605.04920