Efficient Search for Interactive Statistical Machine Translation

Efficient Search for Interactive Statistical Machine Translation Franz Josef Och l and Richard Zens and Hermann Ney Chair of Computer Science VI RWTH Aachen - University of Technology foch,zens,neyl@cs.rwth -aachen.de Abstract The goal of interactive machine transla- tion is to improve the productivity of hu- man translators. An interactive machine translation system operates as follows: the automatic system proposes a transla- tion. Now, the human user has two op- tions: to accept the suggestion or to cor- rect it. During the post-editing process, the human user is assisted by the inter- active system in the following way: the system suggests an extension of the cur- rent translation prefix. Then, the user ei- ther accepts this extension (completely or partially) or ignores it. The two most important factors of such an interactive system are the quality of the proposed extensions and the response time. Here, we will use a fully fledged translation system to ensure the quality of the pro- posed extensions. To achieve fast re- sponse times, we will use word hypothe- ses graphs as an efficient search space representation. We will show results of our approach on the Verbmobil task and on the Canadian Hansards task. 1 Introduction Current machine translation technology is not able to guarantee high quality translations for large do- mains. Hence, in many applications, post-editing 'The author is now affiliated with the Information Science Institute, University of Southern California, och@isi.edu . of the machine translation output is necessary. In such an environment, the main goal of the ma- chine translation system is not to produce transla- tions that are understandable for an inexperienced recipient but to support a professional human post- editor. Typically, a better quality of the produced ma- chine translation text yields a reduced post-editing effort. From an application point of view, many additional aspects have to be considered: the user interface, the used formats and the addi- tional support tools such as lexicons, terminologi- cal databases or translation memories. The concept of interactive machine translation, first suggested by (Foster et al., 1996), finds a very natural implementation in the framework of statis- tical machine translation. In interactive machine translation, the basic idea is to provide an environ- ment to a human translator that interactively reacts upon the input as the user writes or corrects the translation. In such an approach, the system sug- gests an extension of a sentence that the human user either accepts or ignores. An implementation of such a tool was performed in the TransType project (Foster et al., 1996; Foster et al., 1997; Langlais et al., 2000). The user interface of the TransType system combines a machine translation system and a text editor into a single application. The human trans- lator types the translation of a given source text. For each prefix of a word, the machine translation system computes the most probable extension of this word and presents this to the user. The human translator either accepts this translation by press- 387 ing a certain key or …

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