Prompt-Level Reward Specifications for Open-Ended Post-Training

Fuente: arXiv
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Main Authors: Weng, Zijun, Hu, Xiaohui, Song, Shuangyong, Li, Yongxiang, Yu, Kaidong, Huang, Xuanjing
Format: Preprint
Published: 2026
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author Weng, Zijun
Hu, Xiaohui
Song, Shuangyong
Li, Yongxiang
Yu, Kaidong
Huang, Xuanjing
author_facet Weng, Zijun
Hu, Xiaohui
Song, Shuangyong
Li, Yongxiang
Yu, Kaidong
Huang, Xuanjing
contents Open-ended post-training benefits from rewards that make prompt-specific success conditions explicit, rather than relying only on post-hoc scalar scores. In instruction following, writing, and decision-support tasks, response quality depends on local requirements, holistic preferences, and explicit constraints, but existing reward methods often leave these criteria implicit or cover only narrowly verifiable cases. We propose a prompt-level reward specification framework that separates reward specification from reward computation. Given only prompts, our framework constructs reusable task-adaptive rubrics and executable hard-constraint checkers offline, making reward criteria explicit before training and reusable across rollouts. At scoring time, artifact-anchored rubric and code scores are combined with an independent global score for residual holistic quality, yielding a normalized hybrid reward over requirement satisfaction, holistic quality, and deterministic constraints. The framework requires no human preference annotations, reference answers, or a separately trained reward model. Experiments show that the resulting reward improves offline RM-style response ranking and supports online reinforcement learning across multiple open-ended benchmarks. Ablations further show that rubrics, global scoring, and executable verification provide complementary supervision.
format Preprint
id arxiv_https___arxiv_org_abs_2605_29275
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Prompt-Level Reward Specifications for Open-Ended Post-Training
Weng, Zijun
Hu, Xiaohui
Song, Shuangyong
Li, Yongxiang
Yu, Kaidong
Huang, Xuanjing
Computation and Language
Open-ended post-training benefits from rewards that make prompt-specific success conditions explicit, rather than relying only on post-hoc scalar scores. In instruction following, writing, and decision-support tasks, response quality depends on local requirements, holistic preferences, and explicit constraints, but existing reward methods often leave these criteria implicit or cover only narrowly verifiable cases. We propose a prompt-level reward specification framework that separates reward specification from reward computation. Given only prompts, our framework constructs reusable task-adaptive rubrics and executable hard-constraint checkers offline, making reward criteria explicit before training and reusable across rollouts. At scoring time, artifact-anchored rubric and code scores are combined with an independent global score for residual holistic quality, yielding a normalized hybrid reward over requirement satisfaction, holistic quality, and deterministic constraints. The framework requires no human preference annotations, reference answers, or a separately trained reward model. Experiments show that the resulting reward improves offline RM-style response ranking and supports online reinforcement learning across multiple open-ended benchmarks. Ablations further show that rubrics, global scoring, and executable verification provide complementary supervision.
title Prompt-Level Reward Specifications for Open-Ended Post-Training
topic Computation and Language
url https://arxiv.org/abs/2605.29275