A Formal Model for Plausible Dependencies in Lexicalized Tree Adjoining Grammar
Laura Kallmeyer and Marco Kuhlmann. A Formal Model for Plausible Dependencies in Lexicalized Tree Adjoining Grammar. In Proceedings of the 11th International Workshop on Tree Adjoining Grammars and Related Formalisms (TAG+), pages 108–116, Paris, France, 2012.
Several authors have pointed out that the correspondence between LTAG derivation trees and dependency structures is not as direct as it may seem at first glance, and various proposals have been made to overcome this divergence. In this paper we propose to view the correspondence between derivation trees and dependency structures as a tree transformation during which the direction of some of the original edges is reversed. We show that, under this transformation, LTAG is able to induce both ill-nested dependency trees and dependency trees with gap-degree greater than 1, which is not possible under the direct reading of derivation trees as dependency trees.