Graph transformations in dependency parsing have also been used in order to recover nonprojective dependencies together with parsers that are restricted to projective dependency graphs.
nivre and nilsson (2005) improve parsing accuracy for MaltParser by projectivizing training data and applying an inverse transformation to the output of the parser, while Hall and novák (2005) apply post-processing to the output of Charniak's parser (Charniak, 2000).