arXiv:2608.27035cs.CL2026-08

比较韩语句法解析的三种表示方式,发现细粒度信息更助于解析。

Representing and Parsing Korean Constituency Structure at Different Levels of Granularity

  • 用三种不同粒度的韩语结构表示法构建解析数据
  • 词素+词性标注在解析中表现最佳,优于仅以词为单位的表示
  • 尽管以词为终端单位更简洁,但保留词内结构信息更有优势

韩语句法解析面临表征挑战,因其短语结构树的终结符单元并不直接对应简单表面词汇。韩语语素是形态复杂的分隔单位,现有句法资源在如何表示语素内部形态和非显式成分方面存在差异。本文基于宾夕法尼亚韩语树库,比较了三种句法解析表示:词素+词性(Morpheme+XPOS)、语素+词性(Eojeol+XPOS)和语素+统一词性(Eojeol+UPOS)。通过移除空成分、对齐宾夕法尼亚树库的短语结构与显式语素标记、尽可能保留原始标签,并调整终结符与次终结符层来构建这些表示。在统一建模与评估设置下,使用金标准终结符分段与次终结符标签,评估了三种自顶向下、按序、自底向上的非二叉转换型句法解析器。所有实验均在金标准形态句法标注条件下进行。结果显示,以语素为终结符的解析序列更短,但使用语素+UPOS的解析性能显著低于更丰富的形态表示;语素+XPOS缩小了差距,而词素+XPOS在预测后投影到语素域时仍取得最佳结果。该实证发现表明,细粒度形态与词性信息能为解析器提供宝贵证据。这一结论关乎解析可用信息,不决定语言上最优的终结符域。独立来看,语言学与资源设计考虑均支持以语素作为稳定的、可解释的句法标注表面域,同时保留词素级与词性信息作为对齐的形态句法证据。

原文摘要 · Abstract (English)

Korean constituency parsing raises a representational challenge because the terminal units of a phrase-structure tree do not straightforwardly correspond to simple surface words. Korean eojeols are morphologically complex spacing units, and existing constituency resources differ in how they represent eojeol-internal morphology and non-overt elements. This paper compares three constituency parsing representations derived from the Penn Korean Treebank: Morpheme+XPOS, Eojeol+XPOS, and Eojeol+UPOS. We construct these representations by removing null elements, aligning Penn Korean phrase structure with overt eojeol tokens, preserving Penn Korean phrase labels where possible, and varying the terminal and preterminal layers. We then evaluate canonical non-binary transition-based constituency parsers in top-down, in-order, and bottom-up orders under a shared modeling and evaluation setup. All experiments use gold terminal segmentation and gold preterminal labels and therefore evaluate constituency parsing conditioned on gold morphosyntactic annotation. Eojeol terminals yield shorter transition sequences, but Eojeol+UPOS parsing substantially underperforms the morphologically richer conditions. Eojeol+XPOS narrows this gap, while Morpheme+XPOS gives the strongest results even after its predictions are projected to the eojeol terminal domain. Under these gold-annotation conditions, the results show that fine-grained morphological and XPOS representations provide valuable evidence for the evaluated parsers. This empirical finding concerns the information available for parsing and does not by itself determine the linguistically preferable terminal domain. Independently, linguistic and resource-design considerations motivate eojeol as a stable and interpretable surface domain for phrase-structure annotation, with morpheme-level and XPOS information retained as aligned morphosyntactic evidence.

韩语解析句法结构形态标注树库

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