tailieunhanh - Báo cáo khoa học: "Experiments in Parallel-Text Based Grammar Induction"

This paper discusses the use of statistical word alignment over multiple parallel texts for the identification of string spans that cannot be constituents in one of the languages. This information is exploited in monolingual PCFG grammar induction for that language, within an augmented version of the inside-outside algorithm. Besides the aligned corpus, no other resources are required. We discuss an implemented system and present experimental results with an evaluation against the Penn Treebank. . | Experiments in Parallel-Text Based Grammar Induction Jonas Kuhn Department of Linguistics The University of Texas at Austin Austin TX 78712 jonak@ Abstract This paper discusses the use of statistical word alignment over multiple parallel texts for the identification of string spans that cannot be constituents in one of the languages. This information is exploited in monolingual PCFG grammar induction for that language within an augmented version of the inside-outside algorithm. Besides the aligned corpus no other resources are required. We discuss an implemented system and present experimental results with an evaluation against the Penn Treebank. 1 Introduction There have been a number of recent studies exploiting parallel corpora in bootstrapping of monolingual analysis tools. In the information projection approach . Yarowsky and Ngai 2001 statistical word alignment is applied to a parallel corpus of English and some other language F for which no tagger morphological analyzer chunker etc. henceforth simply analysis tool exists. A high-quality analysis tool is applied to the English text and the statistical word alignment is used to project a noisy target annotation to the F version of the text. Robust learning techniques are then applied to bootstrap an analysis tool for using the annotations projected with high confidence as the initial training data. Confidence of both the English analysis tool and the statistical word alignment is taken into account. The results that have been achieved by this method are very encouraging. Will the information projection approach also work for less shallow analysis tools in particular full syntactic parsers An obvious issue is that one does not expect the phrase structure representation of English as produced by state-of-the-art treebank parsers to carry over to less configurational languages. Therefore Hwa et al. 2002 extract a more language-independent dependency structure from the English parse as the basis