Composition Of Transfer Rules In A Multi-Lingual Mt System

The paper describes a software reusability technique relevant to multi-lingualmachine translation systems, which can greatly reduce the eeort needed to construct sets of transfer rules for new language-pairs. If transfer information is coded in a declarative fashion, we show how simple methods borrowed from logic programming can be used to compose two sets of transfer rules for the language-pairs L 1 ! L 2 and L 2 ! L 3 into a new set for the pair L 1 ! L 3. Automatically composed sets of rules are generally of lower quality than hand-coded sets, but can rapidly be improved by hand to an adequate level. We sketch the basic debug-and-test cycle used, and report initial results of experiments in which transfer rule sets for Swedish ! English and English ! French, each of between 1 000 and 1 500 rules, were composed into a set for Swedish ! French. The resulting transfer rules have been used to construct a Swedish-to-French version of the SLT speech translation system.