It will be important to estimate how many attributes are needed for practical applications, e.g., by manually analyzing the use of pattern "C no A" exhaustively for a certain class, C. In addition, since we selected classes that were successfully obtained with a hyponymy acquisition method, we cannot deny the possibility that the proposed method has been evaluated for the classes for which reliable statistics can easily be obtained.
the evaluation of more difficult (e.g., more infrequent) classes will be an important future work.