The parsers are : the Berkeley parser with gold POS tags as input ( Berk-G ) , the Berkeley product parser with two grammars ( Berk-2 ) , the Berkeley parser ( Berk-1 ) , the parser of Zhang and Clark ( 2009 ) ( ZPAR ) , the Bikel parser ( Bikel ) , the Stanford Factored parser ( Stan-F ) , and the Stanford Unlexicalized PCFG parser ( Stan-P ) .