Machine Translation

History of Machine Translation

The translation of natural languages by machine, first dreamt of in the seventeenth century, has become a reality in the late twentieth. Computer programs are producing translations - not perfect translations, for that is an ideal to which no human translator can aspire; nor translations of literary texts, for the subtleties and nuances of poetry are beyond computational analysis; but translations of technical manuals, scientific documents, commercial prospectuses, administrative memoranda, medical reports. Machine translation is not primarily an area of abstract intellectual inquiry but the application of computer and language sciences to the development of systems answering practical needs.

Basic Features and Terminology

A. Definition
The term 'machine translation' (MT) refers to computerized systems responsible for the production of translations with or without human assistance. It is the application of computers to the task of translating texts from one natural language to another. This machine excludes computer-based translation tools which support translators by providing access to on-line dictionaries, remote terminology databanks, transmission and reception of texts, etc.

B. Types of System Design
Generally, there are three basic types of system designs. The first is the 'direct translation' approach in which the MT system is designed in all details specifically for one particular pair of languages, e.g. Russian as the language of the source language, and English as the language of the target language.

The second basic design is the Interlingua approach in which it is possible to convert SL texts into representations common to more than one language. From such Interlingua representations texts are generated into other languages. Translation is thus in two stages: from SL to the Interlingua (IL) and from the IL to the TL. Procedures for SL analysis are intended to be SL-specific and not oriented to any particular TL; likewise programs for TL synthesis are TL-specific and not designed for input from particular SLs. A common argument for the interlingua approach is economy of effort in a multilingual environment. Translation from and into n languages requires n(n-1) bilingual 'direct translation' systems; but with translation via an interlingua just 2n interlingua programs are needed. With more than three languages the Interlingua approach is claimed to be more economic. On the other hand, the complexity of the Interlingua itself is greatly increased. Interlinguas may be based on an artificial language, an auxiliary language such as Esperanto, a set of semantic primitives presumed common to many or all languages, or a 'universal' language-independent vocabulary.

The third basic strategy is the less ambitious transfer approach. Rather than operating in two stages through a single Interlingua representation, there are three stages involving underlying (abstract) representations for both SL and TL texts. The first stage converts SL texts into abstract SL-oriented representations; the second stage converts these into equivalent TL-oriented representations; and the third generates the final TL texts. Whereas the Interlingua approach necessarily requires complete resolution of all ambiguities in the SL text so that translation into any other language is possible, in the transfer approach only those ambiguities inherent in the language in question are tackled; problems of lexical differences between languages are dealt with in the second stage (transfer proper). Transfer systems consist typically of three types of dictionaries (SL dictionary/ies containing detailed morphological, grammatical and semantic information, similar TL dictionary/ies, and a bilingual dictionary relating base SL forms and base TL forms) and various grammars (for SL analysis, TL synthesis and for transformation of SL structures into TL forms).