The impact of our head-word based scoring is analyzed in Table 3, which compares results when only the head word must be correctly identified (as in Table 2) and to results when both the beginning and end of the argument must be correctly identified in the sentence (as in Gildea and Palmer (2002)).
the performance of our CCG system is lowered by the fact that the syntactic analyses in its training corpus differ from those that underlie PropBank in important ways (in particular in the notion of heads and the complement-adjunct distinction).