Interaction between Structural Changes in Machine Translation

Interaction between Structural Changes in Machine Translation Satoshi KINOSHITA, John PHILLIPS, Jun-ichi TSUJII Centre for Computational Linguistics University of Manchester Institute of Science and Technology PO Box 88, Manchester M60 1QD, United Kingdom ABSTRACT This paper discusses complex structural changes dur- ing transfer within a non-destructive transfer framework. Though the description of each individual structural change is not difficult, special provision must be made when they are combined, because interaction between them sometimes causes unexpected problems. Transfer of coordinate struc- tures is also discussed as this often necessitates a structural change and interacts with other structural changes in a prob- lematic way. 1. Introduction Several focal issues have emerged in machine translation (MT) research as the result of recent intensive studies in the field. That is, • Declarative Frameworks for expressing Bi-lingual Knowledge • Integration of Knowledge-based Processing and Contextual Processing with the Translation Process • Effective Exploitation of Domain/Text Type Speci- ficity (or Sublanguageness) in MT and Discovery Processes for such Specificities Though new frameworks of MT such as Statistics-based MT (SBMT), Example-based MT (EBMT), Analogy- based MT (ABMT), Knowledge-based MT (KBMT) etc. look radically different from conventional linguistic- based MT (LBMT) such as Transfer-based, they address one or two of the above focal issues and ignore the rest [7] [9]. In particular, the new paradigms of MT tend to ignore the first issue ie. declarative representation of bi-lingual knowledge and the complexities involved n the process of combining units of bi-lingual knowledge. It is our contention that any MT system, whichever paradigm it belongs to, has to store a set of translation- equivalent units for a pair of languages and combine these to produce larger units of translation. In EBMT, for example, a set of translation examples has to be stored and several of them have to be combined prop- erly to produce translation. Because of the declarative nature of translation examples, EBMT inevitably en- counters the same complexities of combining translation units in declarative representation as LBMT does. Research in LBMT [1] [2] [31 [10] [12] has revealed that difficulties in the declarative representation of bi-lingual knowledge stem mainly from the treatment of idiosyn- cratic structural changes caused by lexical items, and in- teractions of such idiosyncratic structural changes when they co-exist in single sentences. These types of struc- tural changes also cause problems when they are com- bined with general or ordinary linguistic phenomena such as coordination. A formal framework to cope with these matters is essential in other approaches, such as EBMT, as in LBMT, if the translation is produced in a compositional way. In this paper, we discuss problems caused by such in- teraction, and give solutions in our logic-based transfer framework [8]. Our transfer model views the transfer process as deduction; it produces the target linguistic de- scription without changing the source description. This gives a clear contrast to the conventional tree-transducer model, which gradually transforms the source descrip- tion, and is therefore hard to control. Because of the logic oriented nature of …

Content truncated to 500 words