tailieunhanh - Báo cáo khoa học: "Prediction of Thematic Rank for Structured Semantic Role Labeling"

In Semantic Role Labeling (SRL), it is reasonable to globally assign semantic roles due to strong dependencies among arguments. Some relations between arguments significantly characterize the structural information of argument structure. In this paper, we concentrate on thematic hierarchy that is a rank relation restricting syntactic realization of arguments. A loglinear model is proposed to accurately identify thematic rank between two arguments. To import structural information, we employ re-ranking technique to incorporate thematic rank relations into local semantic role classification results. Experimental results show that automatic prediction of thematic hierarchy can help semantic role classification. . | Prediction of Thematic Rank for Structured Semantic Role Labeling Weiwei Sun and Zhifang Sui and Meng Wang Institute of Computational Linguistics Peking University Key Laboratory of Computational Linguistics Ministry of Education China weiwsun@ wm szf @ Abstract In Semantic Role Labeling SRL it is reasonable to globally assign semantic roles due to strong dependencies among arguments. Some relations between arguments significantly characterize the structural information of argument structure. In this paper we concentrate on thematic hierarchy that is a rank relation restricting syntactic realization of arguments. A log-linear model is proposed to accurately identify thematic rank between two arguments. To import structural information we employ re-ranking technique to incorporate thematic rank relations into local semantic role classification results. Experimental results show that automatic prediction of thematic hierarchy can help semantic role classification. 1 Introduction In Semantic Role Labeling SRL it is evident that the arguments in one sentence are highly correlated. For example a predicate will have no more than one Agent in most cases. It is reasonable to label one argument while taking into account other arguments. More structural information of all arguments should be encoded in SRL approaches. This paper explores structural information of predicate-argument structure from the perspective of rank relations between arguments. Thematic hierarchy theory argues that there exists a language independent rank of possible semantic roles which establishes priority among arguments with respect to their syntactic realization Levin and Hovav 2005 . This construct has been widely implicated in linguistic phenomena such as in the subject selection rule of Fillmore s Case Grammar 1968 If there is an A Agent it becomes the subject otherwise if there is an I Instrument it becomes the subject otherwise the subject is the O Object . Patient Theme .