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Main Authors: Orney, Ifdita Hasan, Hamid, Jubayer Ibn, Ramanujam, Shreya S, Wu, Shirley, Hu, Hengyuan, Goodman, Noah, Sadigh, Dorsa, Finn, Chelsea
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2604.17654
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author Orney, Ifdita Hasan
Hamid, Jubayer Ibn
Ramanujam, Shreya S
Wu, Shirley
Hu, Hengyuan
Goodman, Noah
Sadigh, Dorsa
Finn, Chelsea
author_facet Orney, Ifdita Hasan
Hamid, Jubayer Ibn
Ramanujam, Shreya S
Wu, Shirley
Hu, Hengyuan
Goodman, Noah
Sadigh, Dorsa
Finn, Chelsea
contents Exploration is a cornerstone of learning from experience: it enables agents to find solutions to complex problems, generalize to novel ones, and scale performance with test-time compute. In this paper, we present a framework for post-training language models (LMs) that explicitly encourages optimistic exploration and promotes a synergy between exploration and exploitation. The central idea is to train the LM to generate sets of responses that are collectively accurate under the reward function and exploratory in their reasoning strategies. We first develop a general recipe for optimizing LMs with set reinforcement learning (set RL) under arbitrary objective functions, showing how standard RL algorithms can be adapted to this setting through a modification to the advantage computation. We then propose Polychromic Exploratory Policy Optimization (Poly-EPO), which instantiates this framework with an objective that explicitly synergizes exploration and exploitation. Across a range of reasoning benchmarks, we show that Poly-EPO improves generalization, as evidenced by higher pass@$k$ coverage, preserves greater diversity in model generations, and effectively scales with test-time compute.
format Preprint
id arxiv_https___arxiv_org_abs_2604_17654
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Poly-EPO: Training Exploratory Reasoning Models
Orney, Ifdita Hasan
Hamid, Jubayer Ibn
Ramanujam, Shreya S
Wu, Shirley
Hu, Hengyuan
Goodman, Noah
Sadigh, Dorsa
Finn, Chelsea
Artificial Intelligence
Exploration is a cornerstone of learning from experience: it enables agents to find solutions to complex problems, generalize to novel ones, and scale performance with test-time compute. In this paper, we present a framework for post-training language models (LMs) that explicitly encourages optimistic exploration and promotes a synergy between exploration and exploitation. The central idea is to train the LM to generate sets of responses that are collectively accurate under the reward function and exploratory in their reasoning strategies. We first develop a general recipe for optimizing LMs with set reinforcement learning (set RL) under arbitrary objective functions, showing how standard RL algorithms can be adapted to this setting through a modification to the advantage computation. We then propose Polychromic Exploratory Policy Optimization (Poly-EPO), which instantiates this framework with an objective that explicitly synergizes exploration and exploitation. Across a range of reasoning benchmarks, we show that Poly-EPO improves generalization, as evidenced by higher pass@$k$ coverage, preserves greater diversity in model generations, and effectively scales with test-time compute.
title Poly-EPO: Training Exploratory Reasoning Models
topic Artificial Intelligence
url https://arxiv.org/abs/2604.17654