一种改进的汉语语义角色分类体系与标注实践
A Fine-Grained Annotated Dataset for Chinese Semantic-Role Labeling
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摘要: 语义角色标注是自然语言处理中的一项重要任务,涉及文本挖掘、神经网络学习、统计语言学等多个研究领域。在对一个汉语语料库进行语义角色分析时,发现现有的汉语语义角色体系存在一定的局限性。通过引入新的语义角色、吸收和重新定义现有语义角色体系中的语义角色,该文提出了一种改进的汉语语义角色分类体系。该语义角色分类体系将事件中的语义角色分为两大类,即中枢语义角色和周边语义角色,其中,周边语义角色可进一步被细分为主要周边语义角色和辅助周边语义角色。为了减少语义理解的主观性从而客观地判断语义角色类型,该文基于语义和句式以“判断标准-相应例句”的形式详细解释了语义角色分类体系中的主要周边语义角色,并从中枢语义角色半自动化判断、复合动词作中枢语义角色处理、易混淆语义角色难点分析和辅助周边语义角色标注规定等多个方面给出了提高语义角色标注一致性的说明。最后,根据提出的语义角色分类体系对实验语料库进行了语义角色的标注实践,分析了标注一致性,统计了新提出和重定义的主要周边语义角色在语料库中的分布情况,并与基于鲁川语义角色分类体系得到的标注结果进行了对比。Abstract: Semantic roles play an important role in the natural language understanding, but most of the existing semantic-role training datasets are relatively rough or even misleading in labeling semantic roles. In order to facilitate the fine-grained semantic analysis, an improved taxonomy of Chinese semantic roles is proposed by investigating a real-world corpus. Focusing on a corpus formed with sentences with only one pivotal semantic role, we propose a semi-automatic method for fine-grained Chinese semantic role dataset construction. A corpus of 9550 sentences has been labeled with 9423 pivot semantic roles, 29142 principal peripheral semantic roles and 3745 auxiliary peripheral semantic roles. Among them, 172 sentences are double-labeled with semantic roles and 104 sentences are labeled with semantic roles of uncertain semantic events. With a Bi-LSTM+CRF model, we compare the dataset against the Chinese Proposition Bank and reveal differences in the recognition of principal peripheral semantic roles, which provide clues for further improvement.
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