Dependency Parsing and Semantic Role Labeling as a Single Task
Roser Morante, Vincent Van Asch and Antal Van den Bosch
In: 7th International Conference on Recent Advances in Natural Language Processing, 14-16 Sep 2009, Borovets, Bulgaria.
We present a comparison between two systems
for establishing syntactic and semantic depen-
dencies: one that performs dependency parsing
and semantic role labeling as a single task, and
another that performs the two tasks in isola-
tion. The systems are based on local memory-
based classiers predicting syntactic and seman-
tic dependency relations between pairs of words.
In a second global phase, the systems perform
a deterministic ranking procedure in which the
output of the local classiers is combined per
sentence into a dependency graph and seman-
tic role labeling assignments for all predicates.
The comparison shows that in the learning phase
a joint approach produces better-scoring classi-
ers, while after the ranking phase the isolated
approach produces the most accurate syntactic
dependencies, while the joint approach yields the
most accurate semantic role assignments.