Accurate unlexicalized parsing for modern hebrew

Reut Tsarfaty, Khalil Sima'An

פרסום מחקרי: פרק בספר / בדוח / בכנספרסום בספר כנסביקורת עמיתים

תקציר

Many state-of-the-art statistical parsers for English can be viewed as Probabilistic Context-Free Grammars (PCFGs) acquired from treebanks consisting of phrase-structure trees enriched with a variety of contextual, derivational (e.g., markovization) and lexical information. In this paper we empirically investigate the applicability and adequacy of the unlexicalized variety of such parsing models to Modem Hebrew, a Semitic language that differs in structure and characteristics from English. We show that contrary to experience with parsing the WSJ, the markovized, head-driven unlexicalized variety does not necessarily outperform plain PCFGs for Semitic languages. We demonstrate that enriching unlexicalized PCFGs with morphologically marked agreement features percolated up the parse tree (e.g., definiteness) outperforms plain PCFGs as well as a simple head-driven variation on the MH treebank. We further show that an (unlexicalized) head-driven variety enriched with the same features achieves even better performance. We conclude that morphologically rich languages introduce an additional dimension of parametrization that is orthogonal to the horizontal/vertical dimensions proposed before [1] and its contribution is essential and complementary.

שפה מקוריתאנגלית
כותר פרסום המארחText, Speech and Dialogue - 10th International Conference, TSD 2007, Proceedings
מוציא לאורSpringer Verlag
עמודים39-47
מספר עמודים9
מסת"ב (מודפס)9783540746270
מזהי עצם דיגיטלי (DOIs)
סטטוס פרסוםפורסם - 2007
פורסם באופן חיצוניכן
אירוע10th International Conference on Text, Speech and Dialogue, TSD 2007 - Pilsen, צ'כיה
משך הזמן: 3 ספט׳ 20077 ספט׳ 2007

סדרות פרסומים

שםLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
כרך4629 LNAI
ISSN (מודפס)0302-9743
ISSN (אלקטרוני)1611-3349

כנס

כנס10th International Conference on Text, Speech and Dialogue, TSD 2007
מדינה/אזורצ'כיה
עירPilsen
תקופה3/09/077/09/07

טביעת אצבע

להלן מוצגים תחומי המחקר של הפרסום 'Accurate unlexicalized parsing for modern hebrew'. יחד הם יוצרים טביעת אצבע ייחודית.

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