Turning on the Turbo: Fast Third-Order Non-Projective Turbo Parsers

We present fast, accurate, direct nonprojective dependency parsers with thirdorder features. Our approach uses AD3 , an accelerated dual decomposition algorithm which we extend to handle specialized head automata and sequential head bigram models. Experiments in fourteen languages yield parsing speeds competitive to projective parsers, with state-ofthe-art accuracies for the largest datasets (English, Czech, and German)