TAILIEUCHUNG - Báo cáo khoa học: "AN EFFICIENT PARSING ALGORITHM FOR TREE ADJOINING GRAMMARS"

In the literature, Tree Adjoining Grammars (TAGs) are propagated to be adequate for natural language description - - analysis as well as generation. In this paper we concentrate on the direction of analysis. Especially important for an implementation of that task is how efficiently this can be done, ., how readily the word problem can be solved for TAGs. Up to now, a parser with O(n 6) steps in the worst case was known where n is the length of the input string. In this paper, the result is improved to O(n 4 log n) as a new lowest. | AN EFFICIENT PARSING ALGORITHM FOR TREE ADJOINING GRAMMARS Karin Harbusch DFKI - Deutsches Forschungszentrum fur Kũnstỉiche Intelligenz Stuhlsatzenhausweg 3 D-6600 Saarbrucken 11 . harbusch@ de ABSTRACT In the literature Tree Adjoining Grammars TAGs are propagated to be adequate for natural language description analysis as well as generation. In this paper we concentrate on the direction of analysis. Especially important for an implementation of that task is how efficiently this can be done . how readily the word problem can be solved for TAGs. Up to now a parser with 0 ne steps in the worst case was known where n is the length of the input string. In this paper the result is improved to 0 n4 log n as a new lowest upper bound. The paper demonstrates how local interpretion of TAG trees allows this reduction. 1 INTRODUCTION Compared with the formalism of contexi-free grammars CFGs the rules of Tree Adjoining Grammars TAGs can be imagined intuitively as parts of context-free derivation trees. Without paying attention to the fact that there are some more restrictions for these rules the recursion operation adjoining is represented as replacing a node in a TAG rule by another TAG rule so that larger derivation trees are built. This close relation between CFGs and TAGs can imply that they are equivalent. But TAGs are more powerful than context-free grammars. This additional power characterized as mildly context-sensitive leads to the question of whether there are efficient algorithms to solve the word problem for TAGs. Up to now the algorithm of Vijay-Shanker and Joshi with a time complexity of 0 n6 for the worst case was known in addition to several unsuccessful attempts to improve this result. This paper s main emphasis is on the improvement of this result. An efficient parser for Tree Adjoining Grammars with a worst case time complexity of 0 n4 log n is discussed. All known parsing algorithms for TAGs use the close structural similarity between TAGs

• Báo cáo khoa học
• AN EFFICIENT PARSING ALGORITHM
• TREE ADJOINING GRAMMARS
• Karin Harbusch
• 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
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• 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
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• Individuals in Natural
• Language Understanding
• The Use of Ooject Special Knowledge
• Natural Language Processing
• Mark H
• Bursteln