Syntactic Choice In Language Generation

A considerable amount of study has recently been concentrated on the use of linguistically motivated unification based grammars for sentence generation (see for example Appelt 1987, Calder 1989, Shieber 1988, Shieber et al. 1989). The grammars state correspondences between semantic structures and syntactic ones. In most grammars, several syntactic structures will correspond to each semantic one. It was suggested at a fairly early stage that control over which sentence is generated could be applied by adding "functional" features to the grammar. This idea has been extended in the work presented here. T h e use of feature threading techniques allows control over a wide range of syntactic structures, in a fairly sophisticated grammar, while avoiding the need for rule duplication even when generating unbounded dependencies. However, we will see that the feature system required quickly becomes complex, and: may be difficult to extend to more comprehensive grammars.