2001 Fiscal Year Final Research Report Summary
The application of Formal Language Theory to Natural Language Processing
| Project/Area Number |
10680341
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
計算機科学
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| Research Institution | The University of Electro-Communications |
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Principal Investigator |
KASAI Takumi The University of Electro-Communications, Faculty of Electro-Communications, Professor, 電気通信学部, 教授 (70027382)
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| Co-Investigator(Kenkyū-buntansha) |
HASUNUMA Toru The University of Electro-Communications, Faculty of Electro-Communications, Research Assistant, 電気通信学部, 助手 (30313406)
TAKENAGA Yasuhiko The University of Electro-Communications, Faculty of Electro-Communications, Associate Professor, 電気通信学部, 助教授 (20236491)
IWATA Shigeki The University of Electro-Communications, Faculty of Electro-Communications, Professor, 電気通信学部, 教授 (80102028)
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| Project Period (FY) |
1998 – 2001
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| Keywords | Formal Languages / Automata / Tree Automata / Complexity / TAG / Natural Languages / Context-Free |
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| Research Abstract |
We introduced a restricted model of context-free tree grammars called spine grammars, and studied their formal properties including considerably simple normal forms. Recent research on natural languages has suggested that formalisms for natural languages need to generate a slightly larger class of languages than context-free grammars, and for that reason tree adjoining grammars have been widely studied relating them to natural languages. It was shown that the class of string languages generated by spine grammars coincides with that of tree adjoining grammars. We also introduced acceptors called linear pushdown tree automatas are obtained from pushdown tree automata with restriction on duplicability for the pushdown stacks. We also investigated learning theory and obtained a polynomial time inference algorithm for Moore type sequential machines. Further we also investigated the automata models for tree adjoining grammars and introduced a model called transfer pushdown automata.
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