The third variable, z j , encodes the information provided by the parser: it is 1 with cost c S j = −log(P (SU BJ|j)) if the parser thinks that verb j has an explicit subject with probability P (SU BJ|j), otherwise it is 0. subject to The crucial fact about the relation between z j and y j is that a verb has either a syntactically realized NP or a zero pronoun as a subject, but not both.
we considered as pseudo-mentions all bunsetsu chunks (i.e.