An Approach to Sentence-Level Anaphora in Machine Translation

AN APPROACH TO SENTENCE-LEVEL ANAPHORA IN MACHINE TRANSLATION Gertjan van Noord, Joke Dorrepaal, Doug Arnold Steven Krauwer, Louisa Sadler, Louis des Tombe Foundation of Language Technology State University of Utrecht Trans 10 3512 JK Utrecht Dept of Language and Linguistics University of Essex, Wivenhoe Park, Colchester, C04 3SQ, UK. February 15, 1989 Abstract Theoretical research in the area of machine translation usu- ally involves the search for and creation of an appropriate formalism. An important issue in this respect is the way in which the compositionality of translation is to be defined. In this paper, we will introduce the anaphoric component of the Mimo formalism. It makes the definition and trans- lation of anaphoric relations possible, relations which are usually problematic for systems that adhere to strict com- positionality. In iVlimo, the translation of anaphoric rela- tions is compositional. The anaphoric component is used to define linguistic phenomena such as wh-movement, the passive and the binding of reflexives and pronouns mono- lingually. The actual working of the component will be shown in this paper by means of a detailed discussion of wh-movement. Introduction Theoretical research as part of machine translation often aims at finding an appropriate formalism. One of the main issues involved is whether the formalism does full justice to the idea that the translation of a whole is built from the translation of its parts on the one hand and whether it leaves enough room for the treatment of exceptions on the other hand. In other words, the question is in what way the idea of compositionality is to be defined within a particular formalism. An answer to this question from an interlingual perspective is given in the literature on the Rosetta system (e.g. Landsbergen 1985). The CAT frame- work (e.g. Arnold et a]. 1986) was meant to be an an- swer to the same question, this time for a transfer system, viz. the Eurotra system. The MiMo formalism is a re- action to the CAT framework and tries to solve several translation problems by formulating an alternative defini- tion of compositionality. Phenomena involving anaphora I such as wh-movement and the coindexation of pronomi- nais often cause problems for strictly compositional systems since translation of one word depends on (the translation of) another word, one which can be quite far away in the sentence. Rosetta tackles this problem by distinguishing between rules that are significant with respect to the com- posRionality of translation, so-called meaningful rules, and rules that are not, referred to as transformations (Appelo et al. 1987); in this way the system is not compositional in the strict sense anymore. The notion of compositlonaUty MiMo adheres to is defined in such a way that anaphoric relations can be translated compositionally as well. In this paper we wiLi introduce the anaphoric component of the MiMo formalism. It is used to define Linguistic phenomena such as wh-movement, the binding of reflexives and pro- nouns, the passive and control phenomena monolinguaLiy. The formalism will be discussed by means of …

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