tailieunhanh - Báo cáo khoa học: "Robust VPE detection using Automatically Parsed Text"

This paper describes a Verb Phrase Ellipsis (VPE) detection system, built for robustness, accuracy and domain independence. The system is corpus-based, and uses machine learning techniques on free text that has been automatically parsed. Tested on a mixed corpus comprising a range of genres, the system achieves a 70% F1-score. This system is designed as the first stage of a complete VPE resolution system that is input free text, detects VPEs, and proceeds to find the antecedents and resolve them. . | Robust VPE detection using Automatically Parsed Text Leif Arda Nielsen Department of Computer Science King s College London nielsen@ Abstract This paper describes a Verb Phrase Ellipsis VPE detection system built for robustness accuracy and domain independence. The system is corpus-based and uses machine learning techniques on free text that has been automatically parsed. Tested on a mixed corpus comprising a range of genres the system achieves a 70 F1-score. This system is designed as the first stage of a complete VPE resolution system that is input free text detects VPEs and proceeds to find the antecedents and resolve them. 1 Introduction Ellipsis is a linguistic phenomenon that has received considerable attention mostly focusing on its interpretation. Most work on ellipsis Fiengo and May 1994 Lappin 1993 Dalrymple et al. 1991 Kehler 1993 Shieber et al. 1996 is aimed at discerning the procedures and the level of language processing at which ellipsis resolution takes place or ambiguous and difficult cases. The detection of elliptical sentences or the identification of the antecedent and elided clauses within them are usually not dealt with but taken as given. Noisy or missing input which is unavoidable in NLP applications is not dealt with and neither is focusing on specific domains or applications. It therefore becomes clear that a robust trainable approach is needed. An example of Verb Phrase Ellipsis VPE which is detected by the presence of an auxiliary verb without a verb phrase is seen in example 1. VPE can also occur with semi-auxiliaries as in example 2. 1 Johns loves his3 wife 2. Bills doesi too. 2 But although he was terse he didn t rage at me 2 the way I expected him to1. Several steps of work need to be done for ellipsis resolution 1. Detecting ellipsis occurrences. First elided verbs need to be found. 2. Identifying antecedents. For most cases of ellipsis copying of the antecedent clause is enough for resolution Hardt 1997 . 3. Resolving