tailieunhanh - Báo cáo khoa học: "Enhancing Unlexicalized Parsing Performance using a Wide Coverage Lexicon, Fuzzy Tag-set Mapping, and EM-HMM-based Lexical Probabilities"

PCFGs can be accurate, they suffer from vocabulary coverage problems: treebanks are small and lexicons induced from them are limited. The reason for this treebank-centric view in PCFG learning is 3-fold: the English treebank is fairly large and English morphology is fairly simple, so that in English, the treebank does provide mostly adequate lexical coverage1 ; Lexicons enumerate analyses, but don’t provide probabilities for them; and, most importantly, the treebank and the external lexicon are likely to follow different annotation schemas, reflecting different linguistic perspectives. . | Enhancing Unlexicalized Parsing Performance using a Wide Coverage Lexicon Fuzzy Tag-set Mapping and EM-HMM-based Lexical Probabilities Yoav Goldberg1 Reut Tsarfaty2 Meni Adler1 Michael Elhadad1 Department of Computer Science Ben Gurion University of the Negev yoavg adlerm elhadad @ 2Institute for Logic Language and Computation University of Amsterdam Abstract We present a framework for interfacing a PCFG parser with lexical information from an external resource following a different tagging scheme than the treebank. This is achieved by defining a stochastic mapping layer between the two resources. Lexical probabilities for rare events are estimated in a semi-supervised manner from a lexicon and large unannotated corpora. We show that this solution greatly enhances the performance of an unlexicalized Hebrew PCFG parser resulting in state-of-the-art Hebrew parsing results both when a segmentation oracle is assumed and in a real-word parsing scenario of parsing unsegmented tokens. 1 Introduction The intuition behind unlexicalized parsers is that the lexicon is mostly separated from the syntax specific lexical items are mostly irrelevant for accurate parsing and can be mediated through the use of POS tags and morphological hints. This same intuition also resonates in highly lexicalized formalism such as CCG while the lexicon categories are very fine grained and syntactic in nature once the lexical category for a lexical item is determined the specific lexical form is not taken into any further consideration. Despite this apparent separation between the lexical and the syntactic levels both are usually estimated solely from a single treebank. Thus while Supported by the Lynn and William Frankel Center for Computer Sciences Ben Gurion University Funded by the Dutch Science Foundation NWO grant number . Post-doctoral fellow Deutsche Telekom labs at Ben Gurion University PCFGs can be accurate they suffer from vocabulary coverage .

• Báo cáo khoa học
• Enhancing Unlexicalized Parsing Performance
• a Wide Coverage Lexicon
• Fuzzy Tag set Mapping
• EM HMM based Lexical Probabilities
• scientific reports
• model language
• process natural language
• Dialog Control
• Natural Language System
• Dialog Control in a Natural Language System
• Expanding the Horizons
• Natural Language Interfaces
• Phil Hayes
• PROSPECTS OR PRACTICAL
• NATURAL LANGUAGE SYSTEMS
• Workshops
• NATURAL LANGUAGE
• INTERACTION WITH MACHINES
• Long Papers
• COMPUTER INTEBFACE DESIGN MURRAY TUROFF DEPARTMENT OF COMPUTER
• IiVFORMATION SCIENCE IIEW JERSEY INSTITUTE OF TECHNOLOGY
• EVALUATION OF NATURAL LANGUAGE
• INTERFACES TO DATABASE SYSTEMS
• A PANEL DISCUSSION
• database query system
• J
• Norwood Crout
• INTERFACES TO DATA BASE SYSTEMS
• Bozena Henisz
• INTERPRETING NATURAL LANGUAGE
• DATABASE UPDATES
• S
• Jermld Kaplan Jim David
• TRANSPORTABLE NATURAL LANGUAGE
• INTERFACES TO DATABASES
• Gary G
• Hendrlx and William H
• Lewis
• DATABASES THEORETICAL
• TECHNICAL ISSUES
• TRANSPORTABLE NATURAL LANGUAGE INTERFACES
• PROBLEMS AND TECHNIQUES
• Barbara J
• Grosz
• THEORETICAL TECHNICAL ISSUES
• NATURAL LANGUAGE ACCESS TO DATABASES
• R
• Petrick
• Domain Independent
• Database Access Systems
• ISSUES IN NATURAL LANGUAGE
• ACCESS TO DATABASES
• A LOGIC PROGRAMMING PERSPECTIVE
• Sharon C
• Salveter David Maier
• PLANNING NATURAL LANGUAGE
• EXPRESSIONS REFERRING
• Douglas E
• Appelt
• THE TEXT SYSTEM
• NATURAL LANGUAGE GENERATION
• Kathleen R
• M
• MENTING A DATABASE
• KNOWLEDGE REPRESENTATION
• THE KEY TO THE SELECTION PROBLEM
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• Jeffrey Conklin David D
• McDonald
• A KNOWLEDGE ENGINEERING
• NATURAL LANGUAGE UNDERSTANDING
• Stuart C
• Shapiro
• NATURAL LANGUAGE TEXTS
• NECESSARILY GRAMMATICAL
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• UNGRAMHATICALITY
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• NATURAL LANGUAGE UNDERSTANDING SYSTEMS
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• Mark H
• Bursteln