Translation Relations and the Combination of Analytical and Statistical Methods in Machine Translation

One of the determining factors in translation relations is semantic compatibility of cooccurring words. Methods for discovering and representing semantic compatibility relations and their role in translation relations are discussed. The methods used are a combination of analytical and statistical methods, and they are all based on an analytical model of translation. Using the case of semantic compatibility as an example, it is argued that in order to achieve progress in linguistics in general and in Machine Translation in particular neither a purely empiricist nor a purely rationalist approach will do, but that a combination of models and methods is required. Introduction The key problem of the theory of Machine Translation (MT) can be formulated as the question whether an algorithm can be devised which translates as well from one language to another as an ideal translator would. This implies that the theory of MT and its components among them a theory of verbal communication and a theory of comparing languages — must be formal theories. That such theories, if they exist, can be simply derived from observed data is an assumption apparently made by some who use statistical methods in linguistics and in particular in MT, and violently denied by Quine (1953) as well as Chomsky (1986). We advocate a pragmatist approach (as in Lehmann, 1973) which allows for abstract theoretical constructs, but we insist that they must have consequences which can be tested. We prefer operational definitions which can be implemented in algorithms used to analyze and generate texts. A key question of the theory of translation is how can we decide whether an utterance in one language is a translation of an utterance in another language, or, since we should admit that translations cannot always be perfect, whether it is a good translation of an utterance in another language. According to Quine (1959) translation amounts to a semantic correlation of sentences. In a realistic theory of translation we must be interested in larger as well as smaller linguistic