선행 발화의 중심 전이를 이용한 영형 생성

Generation of Zero Pronouns using Center Transition of Preceding Utterances

  • 노지은 (포항공과대학교 컴퓨터공학과) ;
  • 나승훈 (포항공과대학교 컴퓨터공학과) ;
  • 이종혁 (포항공과대학교 컴퓨터공학과)
  • 발행 : 2005.10.01

초록

자연스러운 텍스트를 생성하기 위해서는, 한번 언급된 대상을 지시하기 위한 대용화(pronominalization)과정이 필수적이며, 특히 한국어에 빈번히 발생하는 영형(zero pronoun)을 자연스럽게 생성하는 것이 중요하다. 본 논문에서는, 비용기반 중심화 이론(cost-based centering theory)을 적용하여, 선행 발화의 중심 전이(center transition)가 현 발화의 영형에 미치는 영향을 살펴본다. 이를 위해, 영형으로 실현될 수 있는 명사를 중심화 이론에 기반해 문장간 현저성, 문장내 현저성, 문장간/내 현저성을 가지는지의 여부로 4가지 유형(Npair, Ninter, Nintra, Nnon)으로 정의하고, 유형별로 영형 현상을 고찰하였다. 그 결과, 기존에 중심화 이론에서 배제되었던 명사들이 선행 발화의 중심 전이로 설명될 수 있음을 밝혔다. 또, 선행 발화의 중심 전이를 이용한 영형 생성 모델을 구축하여 다양한 자질을 적용한 영형 생성 모델의 성능과 비교하였다.

To generate coherent texts, it is important to produce appropriate pronouns to refer to previously-mentioned things in a discourse. Specifically, we focus on pronominalization by zero pronouns which frequently occur in Korean. This paper investigates zero pronouns in Korean based on the cost-based centering theory, especially focusing on the center transitions of adjacent utterances. In previous centering works, only one type of nominal entity has been considered as the target of pronominalization, even though other entities are frequently pronominalized as zero pronouns. To resolve this problem, and explain the reference phenomena of real texts, four types of nominal entity (Npair, Ninter, Nintra, and Nnon) from centering theory are defined with the concept of inter-, intra-, and pairwise salience. For each entity type, a case study of zero phenomena is performed through analyzing corpus and building a pronominalization model. This study shows that the zero phenomena of entities which have been neglected in previous centering works are explained via the renter transition of the second previous utterance. We also show that in Ninter, Nintra, and Nnon, pronominalization accuracy achieved by complex combination of several types of features is completely or nearly achieved by using the second previous utterance's transition across genres.

키워드

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