Well-Nested Drawings as Models of Syntactic Structure ?

Abstract

Abstract. This paper investigates drawings (totally ordered forests) as models of syntactic structure. It offers a new model-based perspective on lexicalised Tree Adjoining Grammar by characterising a class of drawings structurally equivalent to tag derivations. The drawings in this class are distinguished by a restricted form of non-projectivity (gap degree at most one) and the absence of interleaving substructures (well-nestedness). We demonstrate that well-nested drawings allow for efficient processing by defining a simple constraint language for them and presenting an algorithm that decides in polynomial time whether a formula in that constraint language is satisfiable on a well-nested drawing. 1