Natural language generation in machine translation (MT) based.on the string-tree corres.pondence grammar (STCG)

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Date
1995-10
Authors
Ai Looi, Heng
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Abstract
A Machine Translation (MT) system is the application of computers to the translation of texts from one natural language in.to another. The String-Tree Correspondence Grammar (STCG) is a grammar formalism used as a specification language for writing linguistic programs in MT systems. The formalism derives its properties from its predecessor, the Static Grammar (SG). It is a declarative bidirectional grammar formalism made up of a set of grammar rules for defining a set of string (a language), a set of trees and the mapping (correspondence) between the two. Structured String-Tree Correspondence (SSTC) is a structure specified by a STCG rule which is used formally to record. the explicit mappings between substrings in the string and subtrees in the tree. Generation based on STCG is the process of producing all possible resultant explicit SSTCs from a STCG grammar which begins with the axiom rule(s). A language (strings) can then be obtained from the explicit SSTCs. In this thesis, we aim at building a generator in MT based on the STCG, which is the more basic generation process for the STCG formalism as opposed to the synthesis process in MT. We set the research in this direction so that the process may be better understood not on..l y in formal but .also in algorithmic terms. We hope that the STCG 't generator will serve as a good foundation for the synthesis process in MT. ,ยท;- A formal means of designing the generator is by using inference rules. It is based on the approach by [Tang 94] for analysis in MT based on the STCG, which in tum was inspired by [Shieber 89]. In the propos~ design, the generator relies entirely on the set of inference rules. We also propose a preprocessing phase for the generator for handling cyclic grammars. In this case, the choices for applying the termination parts in non terminating cases caused by the presence of cyclic/recursive rules are put in formal terms. The generator and the preprocessing for the generator are proposed to be implemented using the C language in MPW (Macintosh Programmer's Workshop).
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Language generation , Translation (mt) based , Correspondence grammar (STCG)
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