Reverse Revision and Linear Tree Combination for Dependency Parsing

We propose a parsing method that allows reducing several of these errors, although maintaining a quasi linear complexity. The method consists in two steps: first the sentence is parsed by a deterministic Shift/Reduce parser, then a second deterministic Shift/Reduce parser analyzes the sentence in reverse using additional features extracted from the parse trees produced by the first parser. We introduce an alternative linear combination method. The algorithm is greedy and works by combining the trees top down. The experiments show that in practice its output often outperforms the results produced by calculating the MST.