Instead researchers condition parsing decisions on many other features, such as parent phrase-marker, and, famously, the lexical-head of the phrase (Magerman, 1995; Collins, 1996; Collins, 1997; Johnson, 1998; Charniak, 2000; Henderson, 2003;<cite> Klein and Manning, 2003</cite>; Matsuzaki et al., 2005) (and others) .