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In this paper we present some novel applications of Explanation-Based Learning (EBL) technique to parsing Lexicalized Tree-Adjoining grammars. The novel aspects are (a) immediate generalization of parses in the training set, (b) generalization over recursive structures and (c) representation of generalized parses as Finite State Transducers. A highly impoverished parser called a "stapler" has also been introduced. We present experimental results using EBL for different corpora and architectures to show the effectiveness of our approach. . | Some Novel Applications of Explanation-Based Learning to Parsing Lexicalized Tree-Adjoining Grammars B. Srinivas and Aravind K. Joshi Department of Computer and Information Science University of Pennsylvania Philadelphia PA 19104 USA srini joshi line. cis.upenn.edu Abstract In this paper we present some novel applications of Explanation-Based Learning EBL technique to parsing Lexicalized Tree-Adjoining grammars. The novel aspects are a immediate generalization of parses in the training set b generalization over recursive structures and c representation of generalized parses as Finite State Transducers. A highly impoverished parser called a stapler has also been introduced. We present experimental results using EBL for different corpora and architectures to show the effectiveness of our approach. 1 Introduction In this paper we present some novel applications of the so-called Explanation-Based Learning technique EBL to parsing Lexicalized Tree-Adjoining grammars LTAG . EBL techniques were originally introduced in the Al literature by Mitchell et al. 1986 Minton 1988 van Harmelen and Bundy 1988 . The main idea of EBL is to keep track of problems solved in the past and to replay those solutions to solve new but somewhat similar problems in the future. Although put in these general terms the approach sounds attractive it is by no means clear that EBL will actually improve the performance of the system using it an aspect which is of great interest to US here. Rayner 1988 was the first to investigate this technique in the context of natural language parsing. Seen as an EBL problem the parse of a single sentence represents an explanation of why the sentence is a part of the language defined by the grammar. Parsing new sentences amounts to finding analogous explanations from the training sentences. As a special case of EBL Samuelsson and This work was partially supported by ARO grant DAAL03-89-0031 ARPA grant N00014-90-J 1863 NSF STC grant DIR-8920230 and Ben Franklin .
