Soft Sequence Policy Optimization

Fuente: arXiv
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Main Authors: Glazyrina, Svetlana, Kryzhanovskiy, Maksim, Ischenko, Roman
Format: Preprint
Published: 2026
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author Glazyrina, Svetlana
Kryzhanovskiy, Maksim
Ischenko, Roman
author_facet Glazyrina, Svetlana
Kryzhanovskiy, Maksim
Ischenko, Roman
contents A significant portion of recent research on Large Language Model (LLM) alignment focuses on developing new policy optimization methods based on Group Relative Policy Optimization (GRPO). Two prominent directions have emerged: (i) a shift toward sequence-level importance sampling weights that better align with the sequence-level rewards used in many tasks, and (ii) alternatives to PPO-style clipping that aim to avoid the associated loss of training signal and entropy collapse. We introduce Soft Sequence Policy Optimization, an off-policy reinforcement learning objective that incorporates soft gating functions over token-level probability ratios within sequence-level importance weights. We provide theoretical motivation for SSPO and investigate practical modifications to improve optimization behavior. Empirically, we show that SSPO improves training stability and performance in mathematical reasoning tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2602_19327
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Soft Sequence Policy Optimization
Glazyrina, Svetlana
Kryzhanovskiy, Maksim
Ischenko, Roman
Machine Learning
Artificial Intelligence
A significant portion of recent research on Large Language Model (LLM) alignment focuses on developing new policy optimization methods based on Group Relative Policy Optimization (GRPO). Two prominent directions have emerged: (i) a shift toward sequence-level importance sampling weights that better align with the sequence-level rewards used in many tasks, and (ii) alternatives to PPO-style clipping that aim to avoid the associated loss of training signal and entropy collapse. We introduce Soft Sequence Policy Optimization, an off-policy reinforcement learning objective that incorporates soft gating functions over token-level probability ratios within sequence-level importance weights. We provide theoretical motivation for SSPO and investigate practical modifications to improve optimization behavior. Empirically, we show that SSPO improves training stability and performance in mathematical reasoning tasks.
title Soft Sequence Policy Optimization
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2602.19327