Using Pattern-Action Rules for the Generation of GPSG Structures from MT-Oriented Semantics

In many tactical NL generators the semantic input structure is taken for granted. In this paper, a new approach to multilingual, tactical generation is presented that keeps the syntax separate from the semantics. This allows for the system to be directly adapted to application-dependent representations. In the case at hand, the semantics is specifically designed for sentence-semantic transfer in a machine translation system. The syntax formalism used is Generalized Phrase Structure Grammar (GPSG). The mapping from semantic onto syntactic structures is performed by a set of pattern-action (PA) rules. Each rule matches a piece of the input structure and guides the GPSG structure-building process by telling it which syntax rule(s) to apply. The scope of each PA rule is strictly local, the actions are primitive, and rules can not call each other. These restrictions render the production system approach both highly modular and transparent.