通过隐式思维向量提升语言模型生成效率与推理能力
Latent Thought Models with Variational Bayes Inference-Time Computation
- 引入显式隐含思维向量,用变分贝叶斯框架实现推理时迭代计算
- 增加推理步数可显著提升样本效率,优于传统自回归与离散扩散模型
- 具备少样本上下文推理能力,适合追求高效生成的场景
我们提出一类新型语言模型——隐式思维模型(Latent Thought Models, LTMs),其在隐空间中引入遵循显式先验分布的隐含思维向量,通过Transformer解码器引导地面词元的自回归生成。训练采用经典变分贝叶斯框架下的双速率优化:快速学习局部变分参数以推断隐向量后验分布(推理时计算),慢速学习全局解码器参数。实证研究发现,LTMs具有超越传统大语言模型(LLMs)的新扩展维度,如推理时迭代次数和隐向量数量。通过增加每词训练计算量可提高样本效率,进一步可通过牺牲模型规模换取更多推理步骤获得收益。基于这些扩展特性设计的LTMs,在验证困惑度与零样本语言建模任务中显著优于自回归模型和离散扩散模型,并展现出随模型规模增长的涌现式少样本上下文推理能力,在条件与无条件文本生成中也达到竞争力水平。
原文摘要 · Abstract (English)
We propose a novel class of language models, Latent Thought Models (LTMs), which incorporate explicit latent thought vectors that follow an explicit prior model in latent space. These latent thought vectors guide the autoregressive generation of ground tokens through a Transformer decoder. Training employs a dual-rate optimization process within the classical variational Bayes framework: fast learning of local variational parameters for the posterior distribution of latent vectors (inference-time computation), and slow learning of global decoder parameters. Empirical studies reveal that LTMs possess additional scaling dimensions beyond traditional Large Language Models (LLMs), such as the number of iterations in inference-time computation and number of latent thought vectors. Higher sample efficiency can be achieved by increasing training compute per token, with further gains possible by trading model size for more inference steps. Designed based on these scaling properties, LTMs demonstrate superior sample and parameter efficiency compared to autoregressive models and discrete diffusion models. They significantly outperform these counterparts in validation perplexity and zero-shot language modeling tasks. Additionally, LTMs exhibit emergent few-shot in-context reasoning capabilities that scale with model size, and achieve competitive performance in conditional and unconditional text generation.
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