Modular Organization of Transformational Grammar

Peter-Arno Coppen
Department of Language and Speech
University of Nijmegen
P.A.Coppen@let.kun.nl
 
The Amazon/Casus program is a modular natural language analysis
system that has been under development since the mid-seventies. It
consists of two major parts: the Amazon AGFL grammar that, compiled 
into a parser, is able to analyse Dutch sentences as structuralistically 
motivated constituent structures; and the Casus Transformational 
Grammar that, interpreted by a driver, enriches this structure with 
deeper information like functional tags and traces of moved 
constituents.

Recently, the Amazon/Casus system has been rebuilt from scratch. In this revision operation, the Casus component has undergone an interesting reorganization. Originally, Casus consisted of a network of transformational grammars. A disadvantage of this organization was, that grammatical constructions typically would have to be treated in more than one of these grammars. For example, treatment of passive involved recognition, taking place in an early grammar, and reshuffling of the thematic frame, wich took place in later stages. In the new organization, Casus consists of separate modules, each one treating a linguistic entity. The modules are compiled into a network of grammars, which is treated by the driver.

In this talk, after a brief introduction into the Amazon/Casus system, I will focus on the new organization of the Casus system, and its advantages. I will give examples of separate modules and specific derivations.