The lexical transfer phase is the most crucial step in MT because most of difficult problems are caused by lexical differences between two languages. In order to treat lexical issues systematically in transfer-based MT systems, we introduce the concept of bilingual-sings which are defined by pairs of equivalent monolingual signs. The bilingual signs not only relate the local linguistic structures of two languages but also play a central role in connecting the linguistic processes of translation with knowledge based inferences. .
