PURPOSE: To select plural installation plans from one data type by permitting a knowledge base to contain data type realization knowledge, data type constitutor specification knowledge, realization method decision knowledge and data type constitutor realization knowledge and providing a knowledge control means.

CONSTITUTION: A known data type realization method and the specification description of an unknown data type data type constitutor by data type realization knowledge 11 corresponding to the unknown data type and data type constitutor specification knowledge 12. Then, data type constitutor realization knowledge 14 to be applied is selected by the known data type realization method and the specification description of the unknown data type data constitutor. When information for realizing the unknown data type, unknown data type control information and operators are made minute and the unknown data type data type constitutor is realized. When information for realizing unknown data type is not sufficient, lacking information is inquired of a user. Consequently, plural installation plans can be selected from one data type.