Charts, Interaction-free Grammars, and the Compact Representation of Ambiguity

Recently researchers working in the LFG framework have proposed algorithms for taking advantage of the implicit context-free components of a unification grammar [Maxwell and Kaplan, 1996]. This paper clarifies the mathematical foundations of these techniques, provides a uniform framework in which they can be formally studied and eliminates the need for special purpose runtime datastructures recording ambiguity. The paper posits the identity: Ambiguous Feature Structures = Grammars, which states that (finitely) ambiguous representations are best seen as unification grammars of a certain type, here called "interactionfree" grammars, which generate in a backtrackfree way each of the feature structures subsumed by the ambiguous representation. This work extends a line of research [Billot and Lang, 1989; Lang, 1994] which stresses the connection between charts and grammars: a chart can be seen as a specialization of the reference grammar for a given input string. We show how this...

• Type: Conference
• Year: 1997
• Where: IJCAI
• Authors: Marc Dymetman
• Keywords: Ambiguous Representation, IJCAI 1997, IJCAI 2007, Implicit Context-free Components, Unification Grammars