1. A computer system comprising: a first knowledge base, including a first computer readable medium for storing information representing human-understandable knowledge; second knowledge base, independently provided from the first knowledge base, the second knowledge base including a second computer readable medium for storing information representing computer-understandable knowledge; a first inference device, included in the second knowledge base, for generating a first result indication of a first problem by using the information representing computer-understandable knowledge stored in the second computer readable medium; a control device, including a solution interpreting portion for interpreting the first result generated by the first inference device, and a retrieving condition generating portion for generating at least one of a retrieving condition and criteria for retrieving the information representing human understandable knowledge related to the first result; and a retrieval device, included in the first knowledge base, for retrieving information representing human-understandable knowledge related to the first result from the first computer readable medium in accordance with the at least one of a retrieving condition and criteria generated by the retrieving condition generating portion, wherein said human-understandable knowledge includes at least one of a text, a figure, a sketch, on-line pen input, pointing information, a table, an image, a moving picture, voice, sound and hyper text.