Cross-domain named entity recognition (NER) models are able to cope with the
scarcity issue of NER samples in target domains. However, most of the existing
NER benchmarks lack domain-specialized entity types or do not focus on a
certain domain, leading to a less effective cross-domain evaluation. To address
these obstacles, we introduce a cross-domain NER dataset (CrossNER), a
fully-labeled collection of NER data spanning over five diverse domains with
specialized entity categories for different domains. Additionally, we also
provide a domain-related corpus since using it to continue pre-training
language models (domain-adaptive pre-training) is effective for the domain
adaptation. We then conduct comprehensive experiments to explore the
effectiveness of leveraging different levels of the domain corpus and
pre-training strategies to do domain-adaptive pre-training for the cross-domain
task. Results show that focusing on the fractional corpus containing
domain-specialized entities and utilizing a more challenging pre-training
strategy in domain-adaptive pre-training are beneficial for the NER domain
adaptation, and our proposed method can consistently outperform existing
cross-domain NER baselines. Nevertheless, experiments also illustrate the
challenge of this cross-domain NER task. We hope that our dataset and baselines
will catalyze research in the NER domain adaptation area. The code and data are
available at this https URL

为了解决交叉域命名实体识别 (NER) 任务中样本少的问题，作者提出了一个跨领域 NER 数据集 CrossNER, 进行了一系列实验来探索利用不同级别的领域语料库和预训练策略进行域自适应预训练的有效性，研究表明利用包含领域特定实体的分数语料库并采用更具挑战性的预训练策略对于 NER 的域自适应有益，提出的方法在跨领域 NER 基线上效果更好。

CrossNER: 跨领域命名实体识别的评估

CrossNER: Evaluating Cross-Domain Named Entity Recognition

Existing models for cross-domain named entity recognition (NER) rely on
numerous unlabeled corpus or labeled NER training data in target domains.
However, collecting data for low-resource target domains is not only expensive
but also time-consuming. Hence, we propose a cross-domain NER model that does
not use any external resources. We first introduce a Multi-Task Learning (MTL)
by adding a new objective function to detect whether tokens are named entities
or not. We then introduce a framework called Mixture of Entity Experts (MoEE)
to improve the robustness for zero-resource domain adaptation. Finally,
experimental results show that our model outperforms strong unsupervised
cross-domain sequence labeling models, and the performance of our model is
close to that of the state-of-the-art model which leverages extensive
resources.

本文提出了一种跨领域命名实体识别模型，使用多任务学习和实体专家混合方法，实现了零资源领域自适应，性能优于其他无监督跨域序列标注模型。