Here, P zero (c|v) and P (a i |φ c ) are computed in the detection and resolution phases, respectively (see Figure 1).
since zero pronouns are omitted obligatory cases, whether or not case c is a zero pronoun depends on the extent to which case c is obligatory for verb v. Case c is likely to be obligatory for verb v if c frequently co-occurs with v. we compute P zero (c|v) based on the co-occurrence frequency of v, c pairs, which can be extracted from unannotated corpora.