It first performs the forward Viterbi algorithm to obtain the best sequence, storing the upper bounds that are used for pruning in branch-and-bound.
generative models based on lexicalized PCFgs enjoyed great success as the machine learning framework for full parsing (Collins, 1999;Charniak, 2000), but recently discriminative models attract more attention due to their superior accuracy (Charniak and Johnson, 2005;Huang, 2008) and adaptability to new grammars and languages (Buchholz and Marsi, 2006).