Layer-Based Dependency Parsing

In this paper, a layer-based projective dependency parsing approach is presented. This novel approach works layer by layer from the bottom up. Inside the layer the dependency graphs are searched exhaustively while between the layers the parser state transfers deterministically. Taking the dependency layer as the parsing unit, the proposed parser has a lower computational complexity than graph-based models which search for a whole dependency graph and alleviates the error propagation that transition-based models suffer from to some extent. Furthermore, our parser adopts the sequence labeling models to find the optimal sub-graph of the layer which demonstrates that the sequence labeling techniques are also competent for hierarchical structure analysis tasks. Experimental results indicate that the proposed approach offers desirable accuracies and especially a fast parsing speed.