tailieunhanh - Báo cáo khoa học: "Fully Unsupervised Core-Adjunct Argument Classification"

The core-adjunct argument distinction is a basic one in the theory of argument structure. The task of distinguishing between the two has strong relations to various basic NLP tasks such as syntactic parsing, semantic role labeling and subcategorization acquisition. This paper presents a novel unsupervised algorithm for the task that uses no supervised models, utilizing instead state-of-the-art syntactic induction algorithms. This is the first work to tackle this task in a fully unsupervised scenario. . | Fully Unsupervised Core-Adjunct Argument Classification Omri Abend Institute of Computer Science The Hebrew University omria01@ Ari Rappoport Institute of Computer Science The Hebrew University ari r@c Abstract The core-adjunct argument distinction is a basic one in the theory of argument structure. The task of distinguishing between the two has strong relations to various basic NLP tasks such as syntactic parsing semantic role labeling and subcategorization acquisition. This paper presents a novel unsupervised algorithm for the task that uses no supervised models utilizing instead state-of-the-art syntactic induction algorithms. This is the first work to tackle this task in a fully unsupervised scenario. 1 Introduction The distinction between core arguments henceforth cores and adjuncts is included in most theories on argument structure Dowty 2000 . The distinction can be viewed syntactically as one between obligatory and optional arguments or semantically as one between arguments whose meanings are predicate dependent and independent. The latter cores are those whose function in the described event is to a large extent determined by the predicate and are obligatory. Adjuncts are optional arguments which like adverbs modify the meaning of the described event in a predictable or predicate-independent manner. Consider the following examples 1. The surgeon operated on his colleague . 2. Ron will drop by after lunch . 3. Yuri played football in the park . The marked argument is a core in 1 and an adjunct in 2 and 3. Adjuncts form an independent semantic unit and their semantic role can often be inferred independently of the predicate . after lunch is usually a temporal modifier . Core Omri Abend is grateful to the Azrieli Foundation for the award of an Azrieli Fellowship. roles are more predicate-specific . on his colleague has a different meaning with the verbs operate and count . Sometimes the same argument plays a different role in