1. A knowledge-base computer system comprising: an input section for inputting data and requesting information relative to outputted information; a knowledge base section for storing frame knowledge which includes a plurality of knowledge groups and execution control method information; an inference section including: retrieval inference means for retrieving a frame knowledge for the output information from said knowledge base section, on the basis of the requested information from said input section, and calculating a value of output information corresponding to information selected from the knowledge base section; state information generating means for executing a calculation of a value of output information corresponding to every relationship for every applied condition and generating state information indicative of a state of a result of the executed calculation in turn when the retrieval inference means searches information including a plurality of applied conditions; execution control means for determining an execution of a next applied condition for solution in response to the state information on the basis of the execution control method information; an output section for outputting the result of the executed calculation in said inference section, wherein the state information generating means comprises means for generating state information indicative of impossibility of further calculation in a frame, said execution control means responsive to said information of impossibility of further calculation by continuing a further calculation in a next frame for input information capable of further calculation.