GTT : A General Transducer for Teaching Computational Linguistics

G~T : A GENERAL TRANSDUCER FOR TEACHING C~TIONAL LINGUISTICS P. Shann J.L. Cochard Dalle Molle Institute for Semantic and Cognitive Studies University of Geneva Switzerland ABSTRACT The GTI~syst~m is a tree-to-tree transducer developed for teaching purposes in machine transla- tion. The transducer is a specialized production system giving the linguists the tools for express- ing infon~ation in a syntax that is close to theo- retical linguistics. Major emphasis was placed on developing a system that is user friendly, uniform and legible. This paper describes the linguistic data structure, the rule formalism and the control facilities that the linguist is provided with. 1. INTRODUCTION The GTT-system (Geneva Teaching Transducer)1 is a ger~ral tree-to-tree transducer developed as a tool for training linguists in machine transla- tion and computational linguistics. The transducer is a specialized production system tailored to the requirements of ecmputational linguists providing them with a means of expressing information in a format close to the linguistic theory they are familiar with. GIT has been developed for teaching purposes and cannot be considered as a system for large scale development. A first version has been inple- mented in standard Pascal and is currently running on a Univac 1100/61 and a VAX-780 under UNIX. At present it is being used by a team of linguists for experimental devel~t of an MT system for a special purpose language (Buchmann et al., 1984), and to train students in cc~putational linguistics. 2. THE UNIFORMITY AND SIMPLICITY OF THE SYSTEM As a tool for training ccr~putational linguists, major emphasis was placed on developing a system that is user friendly, uniform, and which provides a legible syntax. One of the important requirements in machine translation is the separation of linguistic data and algorithms (Vauquois, 1975). The linguist should have the means to express his knowledge declaratively without being obliged to mix ~u- This project is sponsored by the Swiss govern- ment. tational algorithms and linguistic data. Produc- tion systems (Rosner, 1983) seem particularly suited to meet such requirements (Johnson, 1982); the production set that expresses the object-level knowledge is clearly separated from the control part that drives the application of the produc- tions. Colmerauer's Q-system is the classic exam- ple of such a uniform production system used for machine translation (Colmerauer, 1970; Chevalier, 1978: TAUM-METEO). The linguistic knowledge is ex- pressed declaratively using the same data structu- re during the whole translation process as well as tb~ sane type of production rules for dictionary entries, morphology, analysis, transfer and gene- ration. The disadvantage of the Q-system is its quite unnatural rule-syntax for non-prrx/rammers and its lack of flexible control mechanism for the user (Vauquois, 1978). In the design of our system the basic uniform sch~re of Q-systems has been followed, but the rule syntax, the linguistic data structure and the control facilities have been modernized according to recent developments in machine translation (Vauquois, 1978; Bo£tet, 1977; Johnson, 1980; Slocan, 1982). These three points will be deve- loped in the next section. 3. DESCRIPTION OF THE SYST~4 3.1 …

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