Intrasentential Resolution of Japanese Zero Pronouns using Pragmatic and Semantic Constraints

Abstract

This paper proposes a method to resolve intrasentential references of Japanese zero pronouns suitable for application in widely used and practical machine translation systems. This method focuses on semantic and pragmatic constraints such as conjunctions, verbal semantic attributes and modal expressions to determine intrasentential antecedents of Japanese zero pronouns. This method is highly effective because the volume of knowledge that must be prepared beforehand is not so large and its precision of resolution is good. This method was realized in Japanese to English machine translation system, ALT-J/E. To evaluate the performance of our method, we conducted a windowed test for 139 zero pronouns with intrasentential antecedents in a sentence set for the evaluation of the performance of Japanese to English machine translation systems (3718 sentences). According to the evaluation, intrasentential antecedents could be resolved correctly for 98% of the zero pronouns examined using rules consistent for intersentential and extrasentential resolution. The accuracy was higher than the accuracy of the centering algorithm which is a conventional method to resolve zero pronouns. By the further examination of the evaluation, we found that this method can achieve high accuracy using relatively simple rules.

Pronoun Translation and Prediction with or without Coreference Links

“…As rule-based anaphora resolution systems reached their maturity in the 1990s (Mitkov, 2002), several early attempts were made to use these methods for MT, especially in situations when pronominal issues must be addressed specifically such as EN/JP translation (Bond and Ogura, 1998;Nakaiwa and Ikehara, 1995). Following the development of statistical methods for anaphora resolution (Ng, 2010), several studies have attempted to integrate anaphora resolution with statistical MT, as reviewed by Hardmeier (2014, Section 2.3.1).…”

Resolving Direct and Indirect Anaphora for Japanese Definite Noun Phrases

“…In contrast to the rule-based approaches such as (Brennan et al 1987;Shalom and J. 1994;Baldwin 1995;Nakaiwa et al 1995a;Okumura and Tamura 1996;Mitkov 1997), empirical, or machine learning-based approaches have been shown to be a cost-efficient solution achieving performance that is comparable to the best performing rule-based systems (Mccarthy and Lehnert 1995;Ge, Hale, and Charniak 1998;Soon et al 2001;Ng and Cardie 2001;Strube and Muller 2003;Iida et al 2005;Yang, Zhou, Su, and Tan 2003, etc.). Most of these studies focus only on the coreference resolution task, particularly in the context of evaluation-oriented research programs such as Message Understanding Conference (MUC) 1 and Automatic Content Extraction (ACE) 2 .…”

A method of creating new valency entries

“…In addition to its uses in resolving parsing ambiguities (Ikehara et al 1991;Korhonen 2002), verb valency information is particularly important for complicated processing such as identification and supplementation of zero pronouns (Nakaiwa and Ikehara 1995;Yamura-Takei et al 2002). However, this information is not encoded in normal human-readable dictionaries, and is hard to enter manually.…”

“…However, even the semi-automatic implementation does not rely on detailed knowledge of the system dictionaries by the analyst. Our method is similar in principle to Ikehara et al (1995) who add useful information to a user dictionary by comparing input word pairs to existing patterns in the system dictionary.…”