Building Japanese-English Dictionary based on Ontology for Machine Translation

This paper describes a semi-automatic method for associating a Japanese lexicon with a semantic concept taxonomy called an ontology, using a Japanese-English bilingual dictionary as a "bridge". The ontology supports emantic processing i a knowledge-based machine tra slation system by providing a set of language-neutral symbols and semantic information. To put the ontology to practical use, lexical items of each language of interest must be linked to appropriate ontology items. The association of ontology items with lexical items of various languages is a process fraught with difficulty: since much of this work depends on the subjective decisions of hu-man workers, large MT dictionaries tend to be subject o some dispersion and inconsistency. The problem we focus on here is how to associate concepts in the ontology with Japanese lexical entities by automatic methods, since it is too difficult to define adequately many concepts manually. We have designed three algorithms to associate a J panese lexicon with the concepts of the ontology automatically: the equivalent-word match, the argument match, and the exam-ple match. We simulated these algorithms for 980 nouns, 860 verbs and 520 adjectives as preliminary experiments. Theal-gorithms axe found to be effective for more than 80 % of the words. 1. In t roduct ion This paper describes a semi-automatic method for asso-ciating a Japanese lexicon with a semantic oncept ax-onomy using a Japanese-English bilingual dictionary as a "bridge", in order to support semantic processing in a knowledge-based machine translation (MT) system. To enhance the semantic processing in MT systems, many system include conceptual networks called ontolo-gies or semantic taxonomies [Bateman, 1990; Carlso