Indexed on: 01 Aug '01Published on: 01 Aug '01Published in: Grammars
This paper addresses the problem of integrating underspecification of the parent (immediate dominance) and the dominance relation into tree-generating grammar formalisms for natural language processing. Retaining the advantages of Tree Adjoining Grammars (TAG), in particular extended domains of locality and a local derivation process, a TAG extension called local Tree Description Grammar (local TDG) is defined that generates tree descriptions. In contrast to earlier tree description based variants of TAG, the possibility of an underspecified dominance relation provides underspecified representations for scope ambiguities. Furthermore, local TDGs allow an adequate treatment of long-distance scrambling in German which is one of the problematic phenomena for TAG.