In these methods, the semantic compatibility between the contexts surrounding an anaphor and its antecedent (e.g., the compatibility of verbs kidnap and release given some arguments) was automatically extracted from raw texts in an unsupervised manner and used as features in a machine learning-based approach.
because the automatically acquired semantic compatibility is not always true or applicable in the context of any pair of an anaphor and its antecedent, the effectiveness of the compatibility features might be weakened.