| { |
| "paper_id": "C86-1024", |
| "header": { |
| "generated_with": "S2ORC 1.0.0", |
| "date_generated": "2023-01-19T13:14:54.318608Z" |
| }, |
| "title": "Lexieal-Functional Transfer: A Transfer Framework in a Machine Translation System Based on LFG", |
| "authors": [ |
| { |
| "first": "Ikuo", |
| "middle": [], |
| "last": "Kudo", |
| "suffix": "", |
| "affiliation": { |
| "laboratory": "", |
| "institution": "CSK Research Institute", |
| "location": { |
| "addrLine": "3-22-17 Higashi-Ikebukuro, Toshima-ku", |
| "postCode": "170", |
| "settlement": "Tokyo", |
| "country": "Japan" |
| } |
| }, |
| "email": "" |
| } |
| ], |
| "year": "", |
| "venue": null, |
| "identifiers": {}, |
| "abstract": "This paper presents a transfer framework called LFT (Lexical-functional Transfer) for a machine translation system based on LFG (Lexical-functional Grammar). The translation process consists of subprocesses of analysis, transfer and generation. We adopt the so called fstructures of LFG as the intermediate representations or interfaces between those subprocesses, thus the transfer process converts a source f-structure into a target fstructure. Since LFG is a grammatical framework for sentence structure analysis of one language, for the purpose, we propose a new framework for specifying transfer rules with LFG schemata, which incorporates corresponding lexical functions of two different languages into an equational representation. The transfer process, therefore, is to solve equations called target f-descriptions derived from the transfer rules applied to the source fstructure and then to produce a target f-structure.", |
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| "paper_id": "C86-1024", |
| "_pdf_hash": "", |
| "abstract": [ |
| { |
| "text": "This paper presents a transfer framework called LFT (Lexical-functional Transfer) for a machine translation system based on LFG (Lexical-functional Grammar). The translation process consists of subprocesses of analysis, transfer and generation. We adopt the so called fstructures of LFG as the intermediate representations or interfaces between those subprocesses, thus the transfer process converts a source f-structure into a target fstructure. Since LFG is a grammatical framework for sentence structure analysis of one language, for the purpose, we propose a new framework for specifying transfer rules with LFG schemata, which incorporates corresponding lexical functions of two different languages into an equational representation. The transfer process, therefore, is to solve equations called target f-descriptions derived from the transfer rules applied to the source fstructure and then to produce a target f-structure.", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "Abstract", |
| "sec_num": null |
| } |
| ], |
| "body_text": [ |
| { |
| "text": "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.", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "Introduction", |
| "sec_num": "1." |
| }, |
| { |
| "text": "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. 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. 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 lookedup 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. Implementation and execution of these processes are very clear and thus there is no need for further explanation.", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "Introduction", |
| "sec_num": "1." |
| }, |
| { |
| "text": "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. 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 < = = = > 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. Therefore the description of the transfer rules are bidirectional since both sides can be a condition part depending on the direction of transferring.", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "Introduction", |
| "sec_num": "1." |
| }, |
| { |
| "text": "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. 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.", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "LFTrepresentative framework", |
| "sec_num": "3." |
| }, |
| { |
| "text": "Even these relationships can be represented with the LFG schema. 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 <XCOMP'. Therefore LFT rule can make two different structures correspond.", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "LFTrepresentative framework", |
| "sec_num": "3." |
| }, |
| { |
| "text": "Furthermore, there is often nothing corresponding between two languages. For example, a infinitive 'to' exists in English, but there is nothing in Japanese. ", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "LFTrepresentative framework", |
| "sec_num": "3." |
| }, |
| { |
| "text": "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.", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "Two-way dictionary", |
| "sec_num": "3.2" |
| }, |
| { |
| "text": "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) -< BE <... >', ( ~\" ACOMP PRED ) = <F, AGER <... >' in the rule (2b). So it is assigned to the 'be' ", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "Two-way dictionary", |
| "sec_num": "3.2" |
| }, |
| { |
| "text": "LFT processing is divided into four phases as shown in Figure 3 . Each phase is described briefly as follows:", |
| "cite_spans": [], |
| "ref_spans": [ |
| { |
| "start": 55, |
| "end": 63, |
| "text": "Figure 3", |
| "ref_id": null |
| } |
| ], |
| "eq_spans": [], |
| "section": "LFT processing mechanism", |
| "sec_num": "4." |
| }, |
| { |
| "text": "(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). ", |
| "cite_spans": [], |
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| "eq_spans": [], |
| "section": "LFT processing mechanism", |
| "sec_num": "4." |
| } |
| ], |
| "back_matter": [ |
| { |
| "text": "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.", |
| "cite_spans": [], |
| "ref_spans": [], |
| "eq_spans": [], |
| "section": "Acknowledgmel~t", |
| "sec_num": null |
| }, |
| { |
| "text": "variables in the condition side correspond to that in the result side. For example, table 5 in the Figure 3 .", |
| "cite_spans": [], |
| "ref_spans": [ |
| { |
| "start": 99, |
| "end": 107, |
| "text": "Figure 3", |
| "ref_id": null |
| } |
| ], |
| "eq_spans": [], |
| "section": "annex", |
| "sec_num": null |
| }, |
| { |
| "text": "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. 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\"-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.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.(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.", |
| "cite_spans": [], |
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| "eq_spans": [], |
| "section": "(fl_ILase4) SolvingLLar~tions:_", |
| "sec_num": null |
| }, |
| { |
| "text": "An English example sentence and its Japanese equivalent sentence are as follows:(1). Tom is eager to play baseball.(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 Figure 5 . (1) Collect all the f-descriptions 'fin PREI))= value's fi'om a source i: structure (Figure 4) . ", |
| "cite_spans": [ |
| { |
| "start": 325, |
| "end": 328, |
| "text": "(1)", |
| "ref_id": "BIBREF0" |
| } |
| ], |
| "ref_spans": [ |
| { |
| "start": 245, |
| "end": 254, |
| "text": "Figure 4", |
| "ref_id": null |
| }, |
| { |
| "start": 314, |
| "end": 322, |
| "text": "Figure 5", |
| "ref_id": null |
| }, |
| { |
| "start": 409, |
| "end": 419, |
| "text": "(Figure 4)", |
| "ref_id": null |
| } |
| ], |
| "eq_spans": [], |
| "section": "Example", |
| "sec_num": "5." |
| } |
| ], |
| "bib_entries": { |
| "BIBREF0": { |
| "ref_id": "b0", |
| "title": "The Mental of Grammatical Relations", |
| "authors": [ |
| { |
| "first": "R", |
| "middle": [ |
| "M" |
| ], |
| "last": "Kaplan", |
| "suffix": "" |
| }, |
| { |
| "first": "J", |
| "middle": [], |
| "last": "Bresnan", |
| "suffix": "" |
| } |
| ], |
| "year": 1982, |
| "venue": "", |
| "volume": "", |
| "issue": "", |
| "pages": "", |
| "other_ids": {}, |
| "num": null, |
| "urls": [], |
| "raw_text": "R.M.Kaplan and J.Bresnan, 'The Mental of Grammatical Relations', MIT Press, 1982.", |
| "links": null |
| } |
| }, |
| "ref_entries": { |
| "FIGREF0": { |
| "text": "Laboratories Musashino-shi, Tokyo, 180, Japan 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. LFG ana|ysis~\" ~\" two-way dictiona r y--~ /Generation F ...........", |
| "uris": null, |
| "type_str": "figure", |
| "num": null |
| }, |
| "FIGREF1": { |
| "text": "-F ............ functional Transfer ) 1) Dictionary looking-up, 2) Conditioning, 3) lnstantiation, 4) Solving target equations Translation model based on Lexical-functional Transfer", |
| "uris": null, |
| "type_str": "figure", |
| "num": null |
| }, |
| "FIGREF2": { |
| "text": "Transfer rules A transfer rule makes two schemata of two languages correspond each other and its general representative framework is as follows: J[ (LFG) schemata ] < = = = > 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: J[(1' SUBJ)=I ]<===>E[( I\"SUBJ)= I ], L ................ J", |
| "uris": null, |
| "type_str": "figure", |
| "num": null |
| }, |
| "FIGREF3": { |
| "text": ")=SUBJJ l' [(tOBJ)= ~ ]<===>J Fit on,l)= J. q L(~ OBJ CASE-NAME)=OBJ -~ [:( ~' PRED)='PI,AY -[ < = = = >J r-( T PREl))='suru \"7 E <( t SUBJX ~ OBJ)>' I l <( ~\" SUBJ)( 1' OBJ)>' l L i( ~ SUBJ CASE-MARKEItl='ba'J J m ( I' OBJ CASE-MARKER)='we' J", |
| "uris": null, |
| "type_str": "figure", |
| "num": null |
| }, |
| "FIGREF4": { |
| "text": "Two schemata in the rule (2.b), E[( 1\" 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.", |
| "uris": null, |
| "type_str": "figure", |
| "num": null |
| }, |
| "FIGREF5": { |
| "text": "..... T. _~ l _~ a_ _ '_P,:.,~,._ ,.21t~ ( ~. j>2 t w_t~, 2 t h 3 ~e.,tea_\u00a2~ (J) a._a J 22 ) .......", |
| "uris": null, |
| "type_str": "figure", |
| "num": null |
| }, |
| "FIGREF6": { |
| "text": "PRED)=\"ram' 7 F( ~\" PltED)='Tomu' E [(TNUM)=SG J < .... >J [( ]' NUM)=SG L( 1' PERSON ) = 3 L ( 1' PERSON ) = 3 i' 8UBJ) = I < .... >J l( ~ SUBJ CASE-MARKER)='ba' L( 1' SUBJ CASE-NAME)=8UBJ (Ruh~2.b) ( ~ ACOMP SUBJ)=( t SUBJ) to)= + < ..... >J J ( t PRED)='tagaru ( T ACOMP SCOMP INF)= + J<( t SUBJ}( ~ XCOMP)>' { T ACOMP PRED)='EAGER <( t sunJ)( t SCOMP)>' ( ~\" PRED)='BE L <( ? SUnJ)( t ACOMP)> _ (Rt e2.e) iR \"(tACOMPSC()MP)= t ] < .... >Z [(~XCOMP)= ~ ] t ~2.d) \" -( i TENSE--)-PRESENT ~< ..... >J[l ' TENSE) = PRESENT' ASPEC'r)='iru' < ..... >J < OS,l CASE-MARKER)='wo'I ( I\" PRED) = 'I'LAY J OBJ CASE-NAME) = OBJ J . <( t SUBJ)( i' OBJ)>~] ' PRED)= 'etli'tl J <( ~' SUBJ)( ~\" OBJ)>' A (Rule4) ] < = = = >J ' PRED)='yakyuu' E r(t PRED)='bsseball' L( t CAT) = SPORT [I ] ................................ : CA_'\u00a3)--:~y()Ry ............. 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.", |
| "uris": null, |
| "type_str": "figure", |
| "num": null |
| }, |
| "FIGREF7": { |
| "text": "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] < = = = > 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", |
| "uris": null, |
| "type_str": "figure", |
| "num": null |
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| "TABREF0": { |
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| "content": "<table><tr><td colspan=\"3\">English-Japanese dictionary</td><td colspan=\"3\">Japanese-English dictionary</td></tr><tr><td>E:entryl</td><td/><td>/</td><td>~</td><td>J:entryl</td><td>-7</td></tr><tr><td colspan=\"2\">designator ..poin~ers</td><td colspan=\"2\">lransmr rums</td><td colspan=\"2\">pointers [</td></tr><tr><td>E:entry2</td><td colspan=\"4\">E[Schemata]< .... >J[Schemata] J'entry2</td></tr><tr><td>designator</td><td colspan=\"3\">ElSehemata]< = .... >J[Sehemata]</td><td colspan=\"2\">\" designator[</td></tr><tr><td>pointers</td><td colspan=\"3\">E[Schemata]< = .... >J[Scbmnata]</td><td colspan=\"2\">pointers J</td></tr><tr><td/><td colspan=\"4\">Fig.2 example of a two-way dictionary</td></tr><tr><td colspan=\"6\">Table I The English-Japanese dictionary (Ex. from sentence(1) to sentence {2))</td></tr><tr><td>\" Eilglieh entry</td><td/><td>desinator</td><td/><td>pointers</td></tr><tr><td>be</td><td/><td/><td/><td>rule2 a,b,c,d</td></tr><tr><td>eager</td><td/><td colspan=\"2\">(~ ACOMP)= J,</td><td>rule2 a,b,c,d</td></tr><tr><td>Tom</td><td/><td/><td/><td>rule1</td></tr><tr><td>play baseball</td><td/><td>t=$ t=l</td><td/><td>rule3 rule4</td></tr></table>", |
| "text": "..... ,7-L__ ...... , ........ designator]", |
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| "content": "<table><tr><td colspan=\"2\">The Japanese-El~glish dictionary (Ex. from sentence(2) to sentence (1 })</td></tr><tr><td>Japanese entry</td><td>pointers</td></tr><tr><td>tngaru</td><td/></tr><tr><td>tolnil</td><td/></tr><tr><td>8uru</td><td/></tr></table>", |
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