提出连续时间马尔可夫链框架,统一并改进插入式语言模型生成方式。
A Continuous-Time Markov Chain Framework for Insertion Language Models

- 将噪声过程建模为序列空间上的连续时间马尔可夫链,推导出扩散式去噪目标。
- 在合成规划任务中,生成效果优于传统左向生成和掩码扩散模型。
- 采样更灵活,性能媲美主流生成方法,适合需要可控生成的场景。
插入式语言模型(ILMs)相比传统的从左到右生成和基于掩码的生成具有诸多优势。然而,现有插入生成的表述多为临时设计。本文从第一原理出发,将噪声过程建模为变量长度序列空间上的连续时间马尔可夫链,推导出一种扩散风格的去噪目标。我们证明,先前的ILM表述可视为该去噪框架的特例。在合成规划任务上的实证评估表明,所提方法在保留插入生成优势的同时,性能优于左向生成与掩码扩散模型。在语言建模任务中,该扩散方法表现与左向生成和掩码扩散模型相当,同时相较于现有ILMs提供了更高的采样灵活性。
原文摘要 · Abstract (English)
Insertion Language Models (ILMs) offer several advantages over left-to-right generation and mask-based generation. However, existing formulations of insertion-based generation have largely been ad-hoc. In this paper, we derive a diffusion-style denoising objective for ILMs from first principles by formulating the noising process as a continuous-time Markov chain on the space of variable-length sequences. We show that previous formulations of ILMs can be viewed as special cases of this denoising framework. Through empirical evaluation on a synthetic planning task, we show that the proposed approach retains the benefits of insertion-based generation over left-to-right generation and masked diffusion models. In language modeling, our diffusion-based approach is competitive with left-to-right generation and masked diffusion models, while offering additional flexibility in sampling compared to existing insertion language models.
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