TAILIEUCHUNG - Báo cáo khoa học: "Unsupervised Methods for Head Assignments"

We present several algorithms for assigning heads in phrase structure trees, based on different linguistic intuitions on the role of heads in natural language syntax. Starting point of our approach is the observation that a head-annotated treebank defines a unique lexicalized tree substitution grammar. This allows us to go back and forth between the two representations, and define objective functions for the unsupervised learning of head assignments in terms of features of the implicit lexicalized tree grammars. We evaluate algorithms based on the match with gold standard head-annotations, and the comparative parsing accuracy of the lexicalized grammars they give. | Unsupervised Methods for Head Assignments Federico Sangati Willem Zuidema Institute for Logic Language and Computation University of Amsterdam the Netherlands zuidema @ Abstract We present several algorithms for assigning heads in phrase structure trees based on different linguistic intuitions on the role of heads in natural language syntax. Starting point of our approach is the observation that a head-annotated treebank defines a unique lexicalized tree substitution grammar. This allows us to go back and forth between the two representations and define objective functions for the unsupervised learning of head assignments in terms of features of the implicit lexical-ized tree grammars. We evaluate algorithms based on the match with gold standard head-annotations and the comparative parsing accuracy of the lexicalized grammars they give rise to. On the first task we approach the accuracy of hand-designed heuristics for English and interannotation-standard agreement for German. On the second task the implied lex-icalized grammars score 4 points higher on parsing accuracy than lexicalized grammars derived by commonly used heuristics. 1 Introduction The head of a phrasal constituent is a central concept in most current grammatical theories and many syntax-based NLP techniques. The term is used to mark for any nonterminal node in a syntactic tree the specific daughter node that fulfills a special role however theories and applications differ widely in what that special role is supposed to be. In descriptive grammatical theories the role of the head can range from the determinant of agreement or the locus of inflections to the governor that selects the morphological form of its sister nodes or the constituent that is distributionally equivalent to its parent Corbett et al. 2006 . In computational linguistics heads mainly serve to select the lexical content on which the probability of a production should depend Char-niak 1997 Collins 1999 . With the .

• Báo cáo khoa học
• Unsupervised Methods
• Head Assignments
• Federico Sangati
• scientific reports
• model language
• process natural language
• Ensemble Methods
• Unsupervised WSD
• Samuel Brody Roberto Navigli Mirella Lapata
• báo cáo khoa học
• mô hình ngôn ngữ
• xử lý ngôn ngữ tự nhiên
• UNSUPERVISED WORD SENSE
• DISAMBIGUATION RIVALING
• SUPERVISED METHODS
• Combining Unsupervised
• Lexical Knowledge Methods
• Word Sense Disambiguation
• A clustering technique
• The Vietnamese word categorization
• The Vietnamese word
• This could be solved
• Solved using unsupervised machine learning methods
• 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
• E
• Jeffrey Conklin David D
• McDonald
• A KNOWLEDGE ENGINEERING
• NATURAL LANGUAGE UNDERSTANDING
• Stuart C
• Shapiro
• NATURAL LANGUAGE TEXTS
• NECESSARILY GRAMMATICAL
• EVEN COMPLETE
• UNGRAMHATICALITY
• EXTRA GRAMMATICALITY
• NATURAL LANGUAGE UNDERSTANDING SYSTEMS
• Taxonomy
• Descriptions
• Individuals in Natural
• Language Understanding
• The Use of Ooject Special Knowledge
• Natural Language Processing
• Mark H
• Bursteln