SCSL: a linguistic specification language for MT

SCSI_ : a linguistic specification language for MT paper presented for COLING-86 Bonn, 25-29 August 1986 by R@mi ZAOAC GETA, BP 68 Unlverstt6 de Grenoble 38402 Sa4nt-Martin-d'H~res, FRANCE ABSTRACT Nowadays, Mr systems grow to such a stze that a f i r s t specification step is necessary if we want to be able to master their developement and maintenance, for the software part as well for the linguistic part ("lingwares"). Advocating for a clean separation between linguistic tasks and programming tasks, we f i r s t introduce a specification/ implementation/ validation framework for NLP then SCSL, a language for the specification of analysis and generation modules. KEY-WORDS Machine Translation, Natural Language Processing, Specification Language. I. INTRODUCTION In most Nt_P and second generation MT systems, the information computed during the process is generally represented as abstract trees, very common description tools used in linguistics. The modules implementing the Various steps are written in Specialized Languages for Linguistic Programming (SLLP) (see for example <Vauquots85a>, <NakamureB4>, <S]ocum84>, <Masse4>). In spite of the expressive power of SLLP compared to tradltionnal programming languages such as LISP, the conception and the maintenance of programs become more and more difficult as the complexity of "ltngwares" grows. To take up this challenge, we introduce in the field of computational linguistics the specification/ Implementation/ v a l i d a t i o n framework which has been proved valuable in tradttionnal programming. This leads to the intoductton of new tools and new working methods. The expected benefits for computational linguists are allowing them to facilitate the conception of the linguistic parts of NLP systems, tO increase the speed of realisatton, to trnprove the reliability of the final system and to facilitate the maintenance. Writing an analysis program with a SLLP, the computational linguist must define the set of strings to be analysed, the structural descriptor corresponding to an input string, the strategies used for the computation of the descriptor, the heuristics used for ambiguity choices and the treatment of wrong Inputs (errors). He generally writes a more or less precise and comprehensive document on those problems and begin programming from scratch. This method is highly unfeasible with large lingwares, We advocate for the use of a more stringent methodology which consist of : I. Specify formally (Ile. using a formal language) the valid inputs and the corresponding outputs : the specification must be comprehensive and neutral with respect to the choices of implementation. At t h i s stage, the computational l i n g u i s t is concerned only with linguistic problems, not with programming. An interpreter for the specification language should be used to write and debug the specification. 2. Specify the implementation choices for data structures and control (decompostton into modules, strategies and heuristics) and the treatement of errors. This specification depends on the Input/output specification and may partially depend on the ktnd of SLLP to he used for implementation. I t should be as formal as possible, at least a …

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