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arXiv 2302.06198cs.CL
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可区分性校准用于上下文学习

Distinguishability Calibration to In-Context Learning

University of Warwick(华威大学);Xiaomi AI Lab(小米人工智能实验室);King’s College London(伦敦国王学院);The Alan Turing Institute(艾伦·图灵研究所)

Hongjing Li, Hanqi Yan, Yanran Li, Li Qian, Yulan He, Lin Gui

AI总结:

针对基于提示的文本分类中预训练语言模型输出嵌入相似导致细粒度类别难区分的问题,提出基于旋转和缩放的特征变换及双曲嵌入的校准方法,在三个数据集上验证了有效性。

摘要:

近年来,基于提示的学习引起了越来越多的关注,在这种学习中,模型可以仅在少量标注实例上进行训练,使其适用于低资源场景。当使用基于提示的学习进行文本分类时,目标是在给定输入文本的情况下,使用预训练语言模型(PLM)预测预定义模板中的缺失标记,该标记可映射到类别标签。然而,基于Transformer架构的PLM倾向于生成相似的输出嵌入,使得难以区分不同的类别标签。当处理涉及许多细粒度类别标签的分类任务时,这一问题进一步加剧。在本工作中,我们通过提出一种基于旋转和缩放的特征变换的校准方法,将PLM编码的嵌入映射到新的度量空间以保证所得嵌入的可区分性,从而缓解这一信息扩散问题,即不同标记在通过Transformer中堆叠的多层自注意力层后共享大部分相似信息。此外,我们利用双曲嵌入的优势,通过从粗到细的度量学习策略捕获细粒度类别相关标记嵌入之间的层次关系,以增强学习到的输出嵌入的可区分性。在三种数据集上的多种设置下进行的大量实验证明了我们方法的有效性。我们的代码可在https://github.com/donttal/TARA找到。

英文摘要:

Recent years have witnessed increasing interests in prompt-based learning in which models can be trained on only a few annotated instances, making them suitable in low-resource settings. When using prompt-based learning for text classification, the goal is to use a pre-trained language model (PLM) to predict a missing token in a pre-defined template given an input text, which can be mapped to a class label. However, PLMs built on the transformer architecture tend to generate similar output embeddings, making it difficult to discriminate between different class labels. The problem is further exacerbated when dealing with classification tasks involving many fine-grained class labels. In this work, we alleviate this information diffusion issue, i.e., different tokens share a large proportion of similar information after going through stacked multiple self-attention layers in a transformer, by proposing a calibration method built on feature transformations through rotation and scaling to map a PLM-encoded embedding into a new metric space to guarantee the distinguishability of the resulting embeddings. Furthermore, we take the advantage of hyperbolic embeddings to capture the hierarchical relations among fine-grained class-associated token embedding by a coarse-to-fine metric learning strategy to enhance the distinguishability of the learned output embeddings. Extensive experiments on the three datasets under various settings demonstrate the effectiveness of our approach. Our code can be found at https://github.com/donttal/TARA.

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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