A New Formalism for Lexical Transfer: Bilingual Sign-Based Formalism

Abstract

The lexical tranfer has been one of major sources of difficulties in MT. Apart from difficulties of selecting appropriate target equivalent words, systematic structural correspondences between two languages are often violated by idiosyncracies of lexical correspondences. We can hardly expect to have systematic theories of lexical tranfer which generalize idiosyncracies in lexical correspondences. What we can do is to prepare a framework in which we can accumulate systematically idiosyncratic knowledge concerned with lexical correspondences. In this paper, we propose a framework based on bilingual signs for lexical transfer. Through definitions of bilingual signs, not only local linguistic structures of two languages but also predicates which are used for specifying extra-linguistic knowledge are related with each othe~. Furthermore, by using explicit specifications of mutual relationships between bilingual signs, the system can formulate meaningful questions. for disambiguating "transfer ambiguities" during lexical transfer. Compared with converntional bilingual dictionaries, our proposed framework has several desirable properties such as declarativeness, reversibility and flexible interface with extralinguistic processings. A rough sketch of the transfer phase which is based on constraint relaxation is also given.