Combining Outputs from Machine Translation Systems By Fahim A. Salim Supervised by: Ing. Zdenek Zabokrtsky, Ph.D Institute of Formal and Applied Linguistics, Charles University in Prague 2010. Abstract: Due to the massive ongoing research there are many paradigms of Machine Translation systems with diverse characteristics. Even systems designed on the same paradigm might perform differently in different scenarios depending upon their training data used and other design decisions made. All Machine Translation Systems have their strengths and weaknesses and often weakness of one MT system is the strength of the other. No single approach or system seems to always perform best, therefore combining different approaches or systems i.e. creating systems of Hybrid nature, to capitalize on their strengths and minimizing their weaknesses in an ongoing trend in Machine Translation research. But even Systems of Hybrid nature has limitations and they also tend to perform differently in different scenarios. Thanks to the World Wide Web and open source, nowadays one can have access to many different and diverse Machine Translation systems therefore it is practical to have techniques which could combine the translation of different MT systems and produce a translation which is better than any of the individual systems....

Cette thèse de doctorat aborde les problématiques de l'estimation de confiance pour la traduction automatique, et de la traduction automatique statistique de la parole spontanée à grand vocabulaire. J'y propose une formalisation du problème d'estimation de confiance, et aborde expérimentalement le problème sous le paradigme de la classification et régression multivariée. Je propose une évaluation des performances des différentes méthodes évoquées, présente les résultats obtenus lors d'une campagne d'évaluation internationale et propose une application à la post-édition par des experts de documents traduits automatiquement. J'aborde ensuite le problème de la traduction automatique de la parole. Après avoir passé en revue les spécificités du medium oral et les défis particuliers qu'il soulève, je propose des méthodes originales pour y répondre, utilisant notamment les réseaux de confusion phonétiques, les mesures de confiances et des techniques de segmentation de la parole. Je montre finalement que le prototype propose rivalise avec des systèmes état de l'art à la conception plus classique / In this thesis I shall deal with the issues of confidence estimation for machine translation and statistical machine translation of large vocabulary spontaneous speech translation. I shall first formalize the problem of confidence estimation. I present experiments under the paradigm of multivariate classification and regression. I review the performances yielded by different techniques, present the results obtained during the WMT2012 internation evaluation campaign and give the details of an application to post edition of automatically translated documents. I then deal with the issue of speech translation. After going into the details of what makes it a very specific and particularly challenging problem, I present original methods to partially solve it, by using phonetic confusion networks, confidence estimation techniques and speech segmentation. I show that the prototype I developped yields performances comparable to state-of-the-art of more standard design

Baigiamajame magistro darbe nagrinėjamos automatinės vertimo sistemos, pagrindiniai jų veikimo principai ir šių sistemų integracijos būdai. Detaliai aprašoma populiarių šiuo metu statistinių vertimo sistemų struktūra, pateikiami šių ir tradicinių (taisyklėmis paremtų) sistemų privalumai ir trūkumai. Pristatomos visos šiuo metu egzistuojančios automatinio vertimo sistemos lietuvių ir anglų kalbų porai, išaiškinami jų privalumai ir trūkumai. Lingvistiniu požiūriu nagrinėjamos lietuvių ir anglų kalbos, išvardinami šių kalbų panašumai, skirtumai ir sunkumai, kylantys verčiant iš vienos kalbos į kitą. Taip pat pateikiami įvairūs automatinio vertimo įvertinimo būdai, įskaitant populiarų BLEU įvertinimo metodą. Išvardinamos ir analizuojamos užsienio autorių siūlomos automatinio vertimo sistemų integracijos architektūros. Apžvelgiami sumaišymo tinklai, kurie naudojami kuriant integruotą vertimo sistemą. Pateikiama originali mišriosios vertimo sistemos įgyvendinimo metodika. Integruota sistema yra praktiškai įgyvendinama. Šios sistemos ir kitų vertimo sistemų anglų ir lietuvių kalbų porai rezultatai yra įvertinami ir palyginami. Atlikus teorinę automatinio vertimo sistemų apžvalgą ir praktiškai įgyvendinus mišriąją vertimo sistemą, pateikiamos baigiamojo darbo išvados ir siūlymai. Darbą sudaro 6 dalys: įvadas, automatinio vertimo sistemų analizė, mišriųjų automatinio vertimo sistemų analizė, mišriosios automatinio vertimo sistemos sukūrimas, išvados, literatūros sąrašas. Darbo apimtis... [toliau žr. visą tekstą] / The Master’s thesis analyses machine translation systems, their principles of operation and the methods used in integrating these systems. The structure of popular statistical machine translation systems, as well as the advantages and disadvantages of such systems is described in detali. The existing machine translation systems for the Lithuanian-English language pair along with their abilities and shortcomings are presented. Lithuanian and English languages are analysed from the linguistic perspective. The similarities and differences between these languages, as well as the difficulties, arising in translating the text from one language to another are discussed. Moreover, different machine translation evaluation methods, including the popular BLEU metric, are reviewed. Various architectures for integrating multiple machine translation systems, offered by foreign authors, are presented and analysed. Confusion networks, which are used in integrating machine translation systems, are discussed. An original method of implementing the hybrid machine translation system is offered. The hybrid system is implemented in practice. The translation results obtained from the created system and the existing systems for the Lithuanian-English language pair are assessed and compared. Finally, after performing the theoretical review of machine translation systems and implementing the hybrid system, conclusions and recommendations are provided. The thesis consists of 6 parts: introduction, the... [to full text]