使用扩散语言模型强化横向思维的扩散思维链
Reinforcing the Diffusion Chain of Lateral Thought with Diffusion Language Models
AI总结:
本文提出横向思维扩散链(DCoLT)推理框架,通过强化学习优化扩散语言模型的逆向扩散中间步骤,在数学和代码生成任务上显著提升了模型推理准确率。
摘要:
我们引入了横向思维扩散链(DCoLT),一种用于扩散语言模型的推理框架。DCoLT将逆向扩散过程中的每个中间步骤视为潜在的“思考”动作,并优化整个推理轨迹,以通过基于结果的强化学习(RL)最大化最终答案正确性的奖励。不同于遵循因果、线性思维过程的传统思维链(CoT)方法,DCoLT允许双向、非线性推理,且对其思维中间步骤的语法正确性无严格规则。我们在两个代表性的扩散语言模型(DLM)上实现了DCoLT。首先,我们选择SEDD作为代表性的连续时间离散扩散模型,其具体得分推导出一个概率策略,以在中间扩散步骤的整个序列上最大化RL奖励。我们进一步考虑离散时间掩码扩散语言模型——LLaDA,并发现预测和取消掩码token的顺序在优化由Plackett-Luce模型定义的基于排序的取消掩码策略模块(UPM)产生的RL动作中起着至关重要的作用。在数学和代码生成任务上的实验表明,仅使用公开数据和16块H800 GPU,DCoLT增强的DLM优于通过SFT或RL甚至两者结合训练的其他DLM。值得注意的是,DCoLT增强的LLaDA在GSM8K、MATH、MBPP和HumanEval上的推理准确率分别提升了+9.8%、+5.7%、+11.4%和+19.5%。
英文摘要:
We introduce the Diffusion Chain of Lateral Thought (DCoLT), a reasoning framework for diffusion language models. DCoLT treats each intermediate step in the reverse diffusion process as a latent "thinking" action and optimizes the entire reasoning trajectory to maximize the reward on the correctness of the final answer with outcome-based Reinforcement Learning (RL). Unlike traditional Chain-of-Thought (CoT) methods that follow a causal, linear thinking process, DCoLT allows bidirectional, non-linear reasoning with no strict rule on grammatical correctness amid its intermediate steps of thought. We implement DCoLT on two representative Diffusion Language Models (DLMs). First, we choose SEDD as a representative continuous-time discrete diffusion model, where its concrete score derives a probabilistic policy to maximize the RL reward over the entire sequence of intermediate diffusion steps. We further consider the discrete-time masked diffusion language model -- LLaDA, and find that the order to predict and unmask tokens plays an essential role to optimize its RL action resulting from the ranking-based Unmasking Policy Module (UPM) defined by the Plackett-Luce model. Experiments on both math and code generation tasks show that using only public data and 16 H800 GPUs, DCoLT-reinforced DLMs outperform other DLMs trained by SFT or RL or even both. Notably, DCoLT-reinforced LLaDA boosts its reasoning accuracy by +9.8%, +5.7%, +11.4%, +19.5% on GSM8K, MATH, MBPP, and HumanEval.
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