We then use Illinois Chunker ( Punyakanok and Roth , 2001 ) 6 to extract more noun phrases from the text and employ Collins head rules ( Collins , 1999 ) to identify their heads .
headdriven statistical models for natural language parsing
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3 ) , we train on a set of candidates with precision larger than 50 % . We then use Illinois Chunker ( Punyakanok and Roth , 2001 ) 6 to extract more noun phrases from the text and employ Collins head rules ( Collins , 1999 ) to identify their heads . When these extracted heads do not overlap with gold mention heads , we treat them as negative examples .
We then use Illinois Chunker ( Punyakanok and Roth , 2001 ) 6 to extract more noun phrases from the text and employ Collins head rules ( @@CITATION ) to identify their heads .