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arXiv 2401.13660cs.CLcs.LG

MambaByte:无 Token 的选择性状态空间模型

MambaByte: Token-free Selective State Space Model

Cornell University(康奈尔大学)

Junxiong Wang, Tushaar Gangavarapu, Jing Nathan Yan, Alexander M. Rush

AI总结:

本文提出 MambaByte,将 Mamba SSM 适配为字节级自回归语言模型,并通过分词草稿与字节验证的投机解码实现 2.6 倍加速。

摘要:

无 token 语言模型直接从原始字节学习,消除了子词分词带来的归纳偏置。然而,以字节为单位处理会导致序列显著变长。在这种情况下,标准自回归 Transformer 的扩展性较差,因为所需的有效内存会随序列长度增加而增长。近期发展的 Mamba 状态空间模型(SSM)提供了一种有吸引力的替代方案,具有固定大小的记忆状态和高效解码能力。我们提出 MambaByte,这是 Mamba SSM 的一种无 token 适配版本,在字节序列上以自回归方式训练。在建模方面,我们表明 MambaByte 在语言建模任务上能够与最先进的子词 Transformer 竞争,甚至优于它们,同时保留无 token 语言模型的优势,例如对噪声的鲁棒性。在效率方面,我们开发了一种投机解码的适配方法,采用分词草稿生成和字节级验证。这使标准 MambaByte 实现的推理速度提升 2.6 倍,显示出与子词 Mamba 相近的解码效率。这些发现确立了 SSM 在实现无 token 语言建模方面的可行性。

英文摘要:

Token-free language models learn directly from raw bytes and remove the inductive bias of subword tokenization. Operating on bytes, however, results in significantly longer sequences. In this setting, standard autoregressive Transformers scale poorly as the effective memory required grows with sequence length. The recent development of the Mamba state space model (SSM) offers an appealing alternative approach with a fixed-sized memory state and efficient decoding. We propose MambaByte, a token-free adaptation of the Mamba SSM trained autoregressively on byte sequences. In terms of modeling, we show MambaByte to be competitive with, and even to outperform, state-of-the-art subword Transformers on language modeling tasks while maintaining the benefits of token-free language models, such as robustness to noise. In terms of efficiency, we develop an adaptation of speculative decoding with tokenized drafting and byte-level verification. This results in a $2.6\times$ inference speedup to the standard MambaByte implementation, showing similar decoding efficiency as the subword Mamba. These findings establish the viability of SSMs in enabling token-free language modeling.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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