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<Paper uid="C86-1024">
  <Title>Lexieal-Functional Transfer: A Transfer Framework in a Machine Translation System Based on LFG</Title>
  <Section position="2" start_page="0" end_page="112" type="intro">
    <SectionTitle>
1. Introduction
</SectionTitle>
    <Paragraph position="0"> A grammatical theory called LFG (Lexical-functional Grammar)Ill is a framework for sentence structure analysis and has a simple framework for representing lexical and grammatical information. It analyzes a sentence in two steps, a phrase structure analysis and a functional structure analysis. The former is a syntactic analysis and produces constituent structures (cstructures). The latter consists of several procedures, attaching lexical functions to components in the cstructure, deriving flmctional equations called functional descriptions (f-descriptions) from them with preserving configurational relationships, and solving these equations to produce a functional structure (f-structure). Those lexical functions are represented by a representative framework called LFG schema.</Paragraph>
    <Paragraph position="1"> We adopt such LFG schema to a representative framework for a dictionary and rules which define functional correspondences between components of two languages. With them the transfer process can be designed as a simple procedure such that its task is only to solve functional equations of the target language and then produce an f-structure of the target language. We propose such a framework called LFT (Lexical-functional Transfer). It consists of both a representative framework for a two-way dictionary and transfer rules and a processing mechanism of transferring an f-structure of source language into an f-structure of target language.</Paragraph>
    <Paragraph position="2"> The representative framework is declarative and then easy to manipulate. The procedure is a mathematical processing and thus enough simple and clear in its nature and executable easily.</Paragraph>
    <Paragraph position="3">  2. Overall construction of translation system  Figure I shows the global construction of the translation system. The whole process is divided into three subprocesses, analysis, transfer and generation as usual translation systems. The analysis process is nothing but LFG analysis.</Paragraph>
    <Paragraph position="4"> LFG ana|ysis~&amp;quot; ~&amp;quot; two- way dictiona r y--~ /Generation</Paragraph>
    <Paragraph position="6"> Fig. 1 Translation model based on Lexical-functional Transfer The transfer process, LFT converts an f-structure of a source language into a corresponding f-structure of a target language. At first, a transfer dictionary is looked-up and transfer rules are selected. Next, the conditions in the rule are checked. If they are satisfied, the schemata of target language in the transfer rule are instantiated. And then the functional descriptions of target language are obtained. They are called the target functional descriptions (target f-descriptions). After setting up the target fdescriptions, the task of the transfer process is reduced to solve them and then produce an f-structure of the target language. The processes of instantiation and solving target f-descriptions are the same mechanism within LFG.</Paragraph>
    <Paragraph position="7"> Implementation and execution of these processes are very clear and thus there is no need for further explanation.</Paragraph>
    <Paragraph position="8"> The generation process is tentatively defined as a linearization process of the structured relationships in the target f-structure and a insertion process of inflected words. However its explanation is beyond the scope of this paper.</Paragraph>
  </Section>
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