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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="3" start_page="112" end_page="112" type="metho">
    <SectionTitle>
3. LFTrepresentative framework
</SectionTitle>
    <Paragraph position="0"/>
    <Section position="1" start_page="112" end_page="112" type="sub_section">
      <SectionTitle>
3.1 Transfer rules
</SectionTitle>
      <Paragraph position="0"> A transfer rule makes two schemata of two languages correspond each other and its general representative framework is as follows: J\[ (LFG) schemata \] &lt; = = = &gt; E\[ (LFG) schemata\]. In the expression, to show what language the schemata belong to, a initial letter of each language is put in front of each square bracket. In this paper, Japanese is signified with 'J', English with 'E'. Examples of the transfer rules are as follows:</Paragraph>
      <Paragraph position="2"> J\[( L~'PRED)::'t'z&amp;quot;I&lt;===&gt;E\[(~ PRED)='Tom'\].</Paragraph>
      <Paragraph position="3"> A metavariablc ~' in the right hand side nmst correspond to that in the left hand side, and also a metavariable ~ in the right hand side must correspond to that in the left hand side. A symbol &lt; = = = &gt; designates that both sides are strictly corresponding. When a rule is referred in the transfier process, if it is, for example, transferring from Japanese into English, the side having 'J' plays like a condition part in a 'IF...THEN...' rule, and vice versa.</Paragraph>
      <Paragraph position="4"> Therefore the description of the transfer rules are bidirectional since both sides can be a condition part depending on the direction of transferring.</Paragraph>
      <Paragraph position="5"> The number of schemata in both sides are not always equal and such an example appears in the rules 3 in the table 3. It can be divided into next three rules. The isolated type is used in a dictionary since it is compact.</Paragraph>
      <Paragraph position="7"> In a f-structure, its structure is represented with hierarchy and function names. Even if the structures between two corresponding f-structures are different, a transfer process must prove well-formed syntactic relationships in the target f-structure. Even these relationships can be represented with the LFG schema.</Paragraph>
      <Paragraph position="8"> For example, the rule (2.c) makes different structures correspond; hierarchy and function names in the rule are different. English side is 'ACOMP SCOMP' but Japanese side is &lt;XCOMP'. Therefore LFT rule can make two different structures correspond.</Paragraph>
      <Paragraph position="9"> Furthermore, there is often nothing corresponding between two languages. For example, a infinitive 'to'  exists in English, but there is nothing in Japanese. Two schemata in the rule (2.b), E\[( 1&amp;quot; ACOMP SCOMP to) = + \], El( 1' ACOMP SCOMP INF)= + \],  represent infinitive 'to'. As another example, there is no gender in Japanese and English noun, but there are genders in French and German. But it is easy to treat the problem because you have only to add the gender's schema to the rule. For example, 'a book' in English corresponds to 'ein Buch' in German.</Paragraph>
      <Paragraph position="10"> E \]' NUM)=SG &lt; = = = &gt;G NUMI =SG SPEC) = A SPEC) = E1N</Paragraph>
    </Section>
  </Section>
  <Section position="4" start_page="112" end_page="113" type="metho">
    <SectionTitle>
GENDER)= NEUTER
</SectionTitle>
    <Paragraph position="0"/>
    <Section position="1" start_page="112" end_page="113" type="sub_section">
      <SectionTitle>
3.2 Two-way dictionary
</SectionTitle>
      <Paragraph position="0"> The LFT utilizes a two-way dictionary which has entries for both languages. Each entry consists of pairs of (1) a designator and (2) some pointers. The designator is a medium to instantiate the schemata in the condition side. The pointer refers a transfer rule. The rule is referred by both languages through each pointer.</Paragraph>
      <Paragraph position="1"> A rule is registered to the ~value' entry of the head schemata, '( ~ PRED)=value'. When a rule has many head schemata, it is assigned to all the 'value' entries redundantly. For example, the idiom 'be eager to' has two head schemata; ( t PRED) - &lt; BE &lt;... &gt;', ( ~&amp;quot; ACOMP PRED ) = &lt;F, AGER &lt;... &gt;' in the rule (2b). So it is assigned to the 'be'</Paragraph>
      <Paragraph position="3"> entry and the 'eager' entry in the table 1. But the designators are different. The 'be' designator is' ~ = 1 ' and the 'eager' designator is '( ? ACOMP )= I ', as shown in table 1.</Paragraph>
      <Paragraph position="4"> 4. LFT processing mechanism LFT processing is divided into four phases as shown in Figure 3. Each phase is described briefly as follows: (phase1) Loohing:uup the dictionary_ Collect all the head f descriptions whose type is '(fn PRED)-value', from a source f-structure. Look-up 'value' in the dictionary one  by one and go to the phase (2).</Paragraph>
      <Paragraph position="5"> (phase2) Conditi~ Check whether the conditions in the rule are satisfied with the source f-structure. If so, go to the phase (3). If not, check the other rules. When a rule is applied ( from English to Japanese ), English side in the rule works the conditions, Japanese side works the result. E \[conditions\] &lt; = = = &gt; J\[results \] (phase3) Instantia.fion: Instantiate the schemata in the  result side with the table of correspondence, which yields target f-descriptions. When actual variables (fl, f2 ..... etc.) are assigned to the metavariables ~, ~ in the results, the table is looked up. The table shows that actual  variables in the condition side correspond to that in the result side. For example, table 5 in the Figure 3.</Paragraph>
      <Paragraph position="6">  (fl_ILase4) SolvingLLar~tions:_ After the phase (1), (2) and (3), collect all the target f-descriptions and solve them by the LFG algorithm, 'from f-descriptions to an f-structure'. So a target f-structure is obtained.</Paragraph>
      <Paragraph position="7">  variables as follows: (phasel) The metavariables t or ~, in the designator: The ' ~ -variable in the designator in the dictionary' is unified with the actual variable ! fn ' in the schema ' (fn PItEI))= value' which is h)oked up. If designator is' ~' -- ,\[ ', assign the same variable ' fn ' to '1&amp;quot;-variable in the designater'. If not,, assign the actual variable unified with the source f-structure. If it is noL found, the conditions are not satisfied.</Paragraph>
      <Paragraph position="8"> iphase2) The metavariables ~ or ~ in the condition side: Assign 'actual variable whicb is assigned ~-variable in the designator during (phase 1)' to ' 1' -variable in the conditions'. Find the actual variables unified with the source f-structure. Assign it unified with the source f-structure to the ~ -variable. If it is not fotmd, the conditions are not satisfied.</Paragraph>
      <Paragraph position="9"> (phase3) The metavariables ~ or ~ in the result side: Find the actual variables in the condition side by corresponding relations ( i' to T, ~ to ~ ) which the rule define. Look up the variable in the table of correspondence. Assign the variable to the metavariable. If there is no variable, assign a new actual variable to the metavariable.</Paragraph>
    </Section>
  </Section>
  <Section position="5" start_page="113" end_page="113" type="metho">
    <SectionTitle>
5. Example
</SectionTitle>
    <Paragraph position="0"> An English example sentence and its Japanese equivalent sentence are as follows: (1). Tom is eager to play baseball.</Paragraph>
    <Paragraph position="1"> (2). t,A t~ ~ ~- I. f:.\]/oT~,~o tomu ha yakyuu we si(suru) tagatteiru(tagaru.). The f-structure of the English sentence is shown in Figure 4, and the f-structure of the Japanese sentence is shown in  'be': Look up 'be' ; (f |PRED )--'BE &lt;... &gt;'. The designator in the dictionary (table 1) is' ~ = $ '. So 1' = $ = ' fl '. Select the rule (2 a, b, c, d) in table 1.</Paragraph>
    <Paragraph position="2"> (2) Check the conditions . Assigo actual variable fl to the metavariable ~'. Unify the schemata of conditions with the f-structure (Figure 4). Then actual variables ~ f2 ' and ~ f4' are assigned to the motavariables ~ and the following f-descriptions are obtained. E \[(flSUBJ)=f2\] E \[(h ACOMP SCOMP)= f4\] All the conditions of the ( rule 2) are satisfied. Write ' f2 ' and ' f4 ' in the table 5 in Figure 4.</Paragraph>
    <Paragraph position="3"> (3) Instantiate the schemata in the result side. For rule (2.a), look up in the table 5. There is no actual variable corresponding to ' fl ' . So assign a new actual vm'iable ' gl ' to the metavariable ~. Write actual variable' gl ' corresponding to' fl' in the table 5.</Paragraph>
    <Paragraph position="4"> E\[(f ISUBJ)= f2\] &lt; .... &gt;J\[(glPREI)) =g2 \] ...(1) lAkewise,we get the other f-descriptions (2) (3) from rule (2.a), the f-descriptions (4), (5) from rule (2.b), the f-descriptions (6) from rule (2.el and the f-descriptions (7), (8) from rule (2.d).</Paragraph>
    <Paragraph position="5"> 'Tom': the f-descriptions (9), (10), (11) are obtained.</Paragraph>
    <Paragraph position="6"> 'eager' : the same f-descriptions (1)...(8) are obtained.</Paragraph>
    <Paragraph position="7"> 'play': the f-descriptions (12)..(18) are obtained.</Paragraph>
    <Paragraph position="8"> 'baseball' : the \['-descriptions (19),(20) are obtained.</Paragraph>
    <Paragraph position="9">  The author would like to thank Prof. Narita of Waseda University, Mr. Ookawa, chairman of CRI (CSK Research Institute) and Mr.Yada, president of CRI for their constant encouragement.</Paragraph>
  </Section>
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