Our system uses Le and Zuidema (2014)'s reranker (Section 4.3).
it is worth noting that, in this case, each phase with iterated reranking could be seen as an approximation of hard-EM (see Equation 2) where the first step is replaced by instead of searching over the treebank space, the search is limited in a neighbour set N(D i ) generated by k-best parser P i .