{ "paper_id": "A97-1047", "header": { "generated_with": "S2ORC 1.0.0", "date_generated": "2023-01-19T02:14:08.773449Z" }, "title": "An English to Turkish Machine Translation System Using Structural Mapping", "authors": [ { "first": "Cigdem", "middle": [ "Keyder" ], "last": "Turhan", "suffix": "", "affiliation": { "laboratory": "", "institution": "East Technical University", "location": { "postCode": "06531", "settlement": "Ankara", "country": "Turkey" } }, "email": "cigdem@ceng@metu.edu.tr" } ], "year": "", "venue": null, "identifiers": {}, "abstract": "This paper describes the design and implementation of an English-Turkish machine translation (MT) system developed as a part of the TU-Language project supported by a NATO Science for Stability Project grant. The system uses a structural transfer approach in translating the domain of IBM computer manuals. The general design of the translation system and a detailed description of the transfer component is presented in this paper.", "pdf_parse": { "paper_id": "A97-1047", "_pdf_hash": "", "abstract": [ { "text": "This paper describes the design and implementation of an English-Turkish machine translation (MT) system developed as a part of the TU-Language project supported by a NATO Science for Stability Project grant. The system uses a structural transfer approach in translating the domain of IBM computer manuals. The general design of the translation system and a detailed description of the transfer component is presented in this paper.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Abstract", "sec_num": null } ], "body_text": [ { "text": "The TU-Language project sponsored by the NATO Science for Stability Programme was started in 1994 to establish computational foundations for the natural language processing research on the Turkish language with the collaboration of the Computer Engineering Department of Middle East Technical University, the Computer Science Department of Bilkent University and ttalici Computing, Inc. The project attempts to perform extensive research on Turkish which will eventually lead to the development of an English to Turkish machine translation system, Turkish language tutorial system, a Turkish dictionary and other software tools to be used in further research.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "In this paper, some issues in translating from English to Turkish languages, the translation domain, the outline of the machine translation system under development, and a detailed description of the transfer component will be presented.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "Morphology and syntax of Turkish are very different from English, therefore, the formalism used to represent English texts has to be altered significantly for Turkish text representation. The Turkish language is characterized as a head final language where the modifier/specifier always precedes the modified/specified. This characteristic also affects the word order of the sentences which can be described as SOV where the verb is positioned at the end. Also, when compared to other languages, Turkish relies more on overt case markings which mark the role of the argument in a sentence. The case markings enables Turkish to have a relatively free wordorder property where every variation in the word order in a sentence results in a different meaning.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Turkish Language", "sec_num": "2" }, { "text": "In the MT system being developed, these and other different characteristics of the Turkish language are handled in the transfer and generation components.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Turkish Language", "sec_num": "2" }, { "text": "As more and more computer companies enter the Turkish market, a growing demand for English to Turkish translation of computer manuals has emerged. Other machine translation systems have also chosen the domain of computer manuals for their translation systems because of the relatively unambiguous and narrow sublanguage used (Tsutsumi, 1986) . Also, in his research, Nasukawa (Nasukawa, 1993) concluded that the statistical analysis of the text in IBM computer manuals showed that 92.6 percent of the words in a computer manual are used in the same word sense which would significantly reduce the problem of lexical ambiguity resolution. Another advantage is that the material in a computer manual is observed to be written as clearly as possible in a relatively narrow area which will hopefully ease the difficult job of understanding and representing the input sentence. As a result of these observations, the TU-Language project team has chosen the IBM computer manuals as their translation domain..", "cite_spans": [ { "start": 325, "end": 341, "text": "(Tsutsumi, 1986)", "ref_id": "BIBREF7" }, { "start": 367, "end": 392, "text": "Nasukawa (Nasukawa, 1993)", "ref_id": "BIBREF6" } ], "ref_spans": [], "eq_spans": [], "section": "Translation Domain", "sec_num": "3" }, { "text": "The English to Turkish MT system under development uses a structural transfer approach which has the following components. First, the English sentence retrieved from the IBM manual is analyzed by the CLE parser (Alshawi and Moore. 1992) to generate an intermediate representat.ion. This representation is mapped onto a recursively embedded case frame which is then input to the transfer module. The transfer module maps the input case fi'ame into the target case frame which is then filtered to be transformed into the required input format of the target language generator. Lastly, the generator maps the Turkish case frame into the Turkish sentence which is then post-edited by a human translator to get. an intelligible and accurate translation.", "cite_spans": [ { "start": 211, "end": 236, "text": "(Alshawi and Moore. 1992)", "ref_id": "BIBREF0" } ], "ref_spans": [], "eq_spans": [], "section": "Machine Translation System", "sec_num": "4" }, { "text": "For analyzing the English input, the (:;ore Language Engine developed by the SRI Cambridge Computer Science Research (:entre was used (Alshawi and Moore: 1992 ). The CLE system has been trained to meet the lexical, syntactic and semantic demands of the IBM corpus. In CLE, explicit intermediate levels of linguistic representation are used in the different phases of the analysis. Following the syntactic and semantic analysis/synthesis which uses the unification-based approach, the quasi logical form (QLF) is developed. QLF can be described as a contextually seT~silive logical form. Since the CLE syst.em produces various parses for an input sentence, the best parse is filtered by the system which conveys the intended meaning of the sentence. Then the chosen representation is mapped into a case frame.", "cite_spans": [ { "start": 134, "end": 158, "text": "(Alshawi and Moore: 1992", "ref_id": "BIBREF0" } ], "ref_spans": [], "eq_spans": [], "section": "Analysis Phase", "sec_num": "4.1" }, { "text": "Experience with previous systems using the interlingua technique showed the significant complexity of extracting and representing deep meaning of a natural language text (Goodman and Nirenburg, 1991) . Another major difficulty encountered with this approach is that the language specific attributes neeessary to define the translation equivalents in the lexical and structural levels are neutralized in the interlingual representation thereby complicating the task of generation considerably.", "cite_spans": [ { "start": 170, "end": 199, "text": "(Goodman and Nirenburg, 1991)", "ref_id": "BIBREF1" } ], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "A similar problem occurred with systems using the transfer approach with deep semantic analysis such as the EUROTRA project (Johnson et al., 1985) . Such systems were observed to be difficult to develop a.nd maintain. To avoid these problems, the MT systems developed recently generally chose to use the straightforward transfer approach which relies on various types of lexical, syntactic information and a limited use of semantic analysis (Tsntsumi, 1986) .", "cite_spans": [ { "start": 124, "end": 146, "text": "(Johnson et al., 1985)", "ref_id": "BIBREF3" }, { "start": 441, "end": 457, "text": "(Tsntsumi, 1986)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "The system being developed as a part of the TU-Language project also chose the structural l.ransfer approach with a minimal amount of semantic analysis. T'he transfer phase of our MT systeln performs structural transfer between the respective case frames of the analysed English sentence and targetted Turkish output. In a top-down manner, the transfer lnodule tra.nsfbrms the English case frame or adds new infbrmatioll to the 'turkish case frame in order to generate the equivalent Turkish noun phrase, clause or sentence with the aid of a transfer dictionary, and the transfer rules.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "The English and Turkish case frames for clauses/sentences are generally similar to each other with differences seen in the sentence's mood and the verb's aspect and modality. Some information not extracted in the analysis phase such as the sentence form, clause type. role, etc. have to be determined in the beginning of the transfer phase and added to the Turkish case frame. An example sentence and parts of the corresponding English and Turkish case frames can be seen below:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "(1) John must show the program works.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "John goster+tns program+gen calis+t.ns 'John progralnin calistigini gostermeli'. (3) Programs were written for the project. Program+pl yaz+pass+pst icin proje 'Proje icin progralnlar yazildi.'", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "Even though the word program is used in the plural form in both of the English sentences, the transfer module needs to determine the specificity of the noun phrase in question and send it to the generator which will accordingly output either the singular or plural form of the noun.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "Some of the complex transfer issues presented by Lindop and Tsujii (Lindop and Tsujii, 1991) also arise in our machine translation system. These issues are handled with special transfer rules and transfer lexicon entries. In the beginning of the transfer phase, the exception rules are tested and eventually a checklist containing the problematic components of the input is generated. Some examples of these components are verbs which change meaning when used with different attributes, passive, existential or conditional sentences, relative clauses, idiomatic use of prepositional phrases, etc. As the transfer process continues, the checklist is referenced in order to block the default translation and handle the exceptions. The rest of the mapping proceeds in a straightforward fashion until all of the information in the source case frame is mapped onto the target case frame.", "cite_spans": [ { "start": 49, "end": 92, "text": "Lindop and Tsujii (Lindop and Tsujii, 1991)", "ref_id": "BIBREF4" } ], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "Some of the complex transfer issues handled in the transfer phase will be presented in this section.First, a significant amount of head-switching is performed to resolve the lexical and structural differences in the English and Turkish languages. In the example below, (4) attempted execution tesebbus calistirma 'calistirma tesebbusu : execution attempt' execution is the head noun of the English phrase whereas tesebbus (attempt) becomes the head noun in the target phrase.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "Another problem encountered in the transfer module is complex lexical transfer with category changes such as the example given below:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "(5) John gave a weak cough. John oksur+pst hafifce 'John hafifce oksurdu.:John coughed weakly.'", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "The adjective weak has to be mapped onto an adverb hafifce and the verb give's default translation into the verb ver has to be blocked when it is used with the dependent noun cough. Consequently, the fitting target verb is found to be oksurmek.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "Also, dependent on the verb, an object of an English sentence may be mapped to different case markings in Turkish.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "(6) I hit the man. vur+pst+pers adam+dat 'Adama vurdum' (7) I shot the man. vur+pst+pers adanl+acc 'Adami vurdum'", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "As seen above,the object of the sentence *be man. is mapped either to a.n accusative marked object adami or a dative marked indirect object adama in the target sentence.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "There are also some complex structural changes encountered during transfer.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "An English clause might be mapped into a Turkish gerund:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "(8) While he was working +ken calis+tns 'Calisirken'", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "Another example of a structural transforlnation encountered can be seen in active/passive forms of sentences. In the English passive tbrm, the surface subject can correspond to both the direct object or the indirect object of the active form. Yet in Turkish, the surface subject of a passive sentence can only be the direct object of the active form. The difference between the two sentences is distinguished by the order of the phrases in the target sentence as seen in the example below:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "(9) This program was given to the user. Bu program ver+pas+pst kullanici+dat 'Bu program kullaniciya verildi.'", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Transfer Phase", "sec_num": "4.2" }, { "text": "The user was given the program.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "(10)", "sec_num": null }, { "text": "In both of the Turkish translations, the surface subject is program whereas the surface subject changes in the English inputs.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Kullanici+dat ver+pas+pst program 'Kullaniciya program verildi'", "sec_num": null }, { "text": "The order of the words in the output sentences are determined by the topic and focus features of the target case frame which are mapped during the transfer phase. In the first sentence, the topic is found to be program, and the focus is kullanici, whereas in the second sentence the topic and the focus are kullanici and program., respectively.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Kullanici+dat ver+pas+pst program 'Kullaniciya program verildi'", "sec_num": null }, { "text": "The transfer module also attacks problelns related to sentential transformation such as the ones required in the example below:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Kullanici+dat ver+pas+pst program 'Kullaniciya program verildi'", "sec_num": null }, { "text": "(11) Other problems encountered in the transfer phase are the lexical gaps, idiomatic uses of phrases, and lexical disambiguation by syntactic or semantic content.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Kullanici+dat ver+pas+pst program 'Kullaniciya program verildi'", "sec_num": null }, { "text": "With all the complex transfer issues resolved in the transfer phase, the corresponding Turkish case frame is generated which is then translated froln its Prolog notation into the Lisp notation required by the generation module.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Kullanici+dat ver+pas+pst program 'Kullaniciya program verildi'", "sec_num": null }, { "text": "The generation component of the system is based on the GenKit environment developed at the Carnegie Mellon University -Center for Machine Translation which provides facilities for a unification-based generation grammar environment (Hakkani et al., 1996) . As input, the generator receives a recursively embedded target case frame representation where all the lexica.1 choices have been made, and produces the Turkish sentence conveying the same meaning.", "cite_spans": [ { "start": 231, "end": 253, "text": "(Hakkani et al., 1996)", "ref_id": "BIBREF2" } ], "ref_spans": [], "eq_spans": [], "section": "Generation Module", "sec_num": "4.3" }, { "text": "Since Turkish has complex agglutinative word forms, a separate morphological generator handles the proper morpheme selection, vowel harmony, etc. to produce the surface form of the generated words.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generation Module", "sec_num": "4.3" }, { "text": "The Turkish sentence output by the generator is post-edited by a. human translator to ensure accuracy and intelligibility of the target sentence.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Generation Module", "sec_num": "4.3" }, { "text": "In this paper, an English to Turkish MT system using the structural transfer approach with a limited amount of semantic analysis has been described. The structural transfer method which uses the recursively embedded case frames as intermediate representation proved to be very suitable in the application of English to Turkish machine translation. The greatest difficulty encountered with this approach is handling the complex transfer issues that arise due to the differences between the two languages.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Conclusion", "sec_num": "5" }, { "text": "Hopefully, the introduction of the English to Turkish MT software into the Turkish market will meet the growing demands for accurate, fast and highquality translations in the field of computer manuals. Depending on the success of the system, the lexicons and the transfer module might be modified to tackle other translation domains in the future. ", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Conclusion", "sec_num": "5" } ], "back_matter": [ { "text": "Helpful comments of Asst.Prof Cem Bozsahin and Assoc.Prof.Mehmet R.Tolun are gratefully acknowledged. This work has been supported by the NATO Science for Stability Project TU-LANGUAGE.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Acknowledgements", "sec_num": null } ], "bib_entries": { "BIBREF0": { "ref_id": "b0", "title": "The Core Language Engine", "authors": [ { "first": "Hiyan", "middle": [], "last": "Alshawi", "suffix": "" }, { "first": "Robert", "middle": [ "C" ], "last": "Moore", "suffix": "" } ], "year": 1992, "venue": "", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Hiyan Alshawi and Robert C. Moore. 1992. In- troduction to the CLE. In Hiyan Alshawi, editor, The Core Language Engine. 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