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arXiv 2005.04908cs.IR
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基于长文本的局部自注意高效文档检索

Local Self-Attention over Long Text for Efficient Document Retrieval

Sebastian Hofstätter, Hamed Zamani, Bhaskar Mitra, Nick Craswell, Allan Hanbury

摘要:

神经网络,特别是基于transformer的架构,在几个检索基准上取得了显着的性能改进。当被检索的项目是文档时,在整个文档术语序列上使用Transformers的时间和存储器成本可能是过高的。一个流行的策略是只考虑文档的前n个项。然而,这可能导致系统有偏见,无法检索较长的文档。在这项工作中,我们提出了一个本地的自我注意力,认为一个移动窗口的文件条款,并为每个条款只出席其他条款在同一个窗口。这种局部注意力引起的计算和内存成本是整个文档的一小部分。窗口化方法还导致在小批量中更紧凑地打包填充的文档,从而导致额外的节省。我们还采用了一个学习的饱和度函数和两阶段池化策略来识别文档的相关区域。具有这些变化的Transformer-Kernel池模型可以有效地从具有数千个标记的文档中提取相关信息。我们对TREC 2019深度学习跟踪的文档排序任务进行了基准测试,并观察到检索质量的显着改善以及在计算和内存成本适度增加的情况下增加了对较长文档的检索。

英文摘要:

Neural networks, particularly Transformer-based architectures, have achieved significant performance improvements on several retrieval benchmarks. When the items being retrieved are documents, the time and memory cost of employing Transformers over a full sequence of document terms can be prohibitive. A popular strategy involves considering only the first n terms of the document. This can, however, result in a biased system that under retrieves longer documents. In this work, we propose a local self-attention which considers a moving window over the document terms and for each term attends only to other terms in the same window. This local attention incurs a fraction of the compute and memory cost of attention over the whole document. The windowed approach also leads to more compact packing of padded documents in minibatches resulting in additional savings. We also employ a learned saturation function and a two-staged pooling strategy to identify relevant regions of the document. The Transformer-Kernel pooling model with these changes can efficiently elicit relevance information from documents with thousands of tokens. We benchmark our proposed modifications on the document ranking task from the TREC 2019 Deep Learning track and observe significant improvements in retrieval quality as well as increased retrieval of longer documents at moderate increase in compute and memory costs.

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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