The local factor for a binary rule r = X → Y Z, over span (i, j), with CCM features F ij = (y ij , c ij ) and prototype feature p ij , is given by the product of local factors for the CCM and CFG+ models: From these local factors, the inside-outside algorithm produces expected counts for each binary rule, r, over each span (i, j) and split point k, denoted by P (r, (i, j), k|S, F, F ).
clearly, we need to do something more than adding structural bias (e.g.