10. A knowledge base system that builds and executes a knowledge base comprising: an apparatus that builds said knowledge base, having: interface means for receiving said knowledge base by a user, said interface means comprising a knowledge sheet, said knowledge sheet comprising: a field that stores an output knowledge variable; input and local fields that store knowledge variables that operate said output knowledge variable; and another field that stores a computing equation of declarative representation that utilizes said knowledge variables, using operands as other knowledge variables; and computer program generating means for generating a computer program in accordance with said knowledge sheet, said computer program generating means comprising: means for translating said computing equation of declarative representation into a computer program; and means for producing attributes of knowledge variables in said knowledge sheet, and an apparatus that executes said knowledge base, having: means for retrieving dependence of said output knowledge variable on other knowledge variables; means for setting an execution sequence of the computer program, with reference to said dependence; and means for making one of an input request to a user and for executing the computer program, wherein said knowledge base building apparatus comprising: means for receiving a scenario for specifying an execution sequence of knowledge sheets; and means for receiving a knowledge sheet serving as an alternate solution when computation of said knowledge sheets of the scenario is a failure, said knowledge base executing means comprising: means for setting an execution sequence of said knowledge sheets in the scenario with references to the scenario; and means for executing said knowledge sheets serving as said alternative solutions when execution of knowledge sheets is a failure and knowledge sheets serving as alternative solutions are specified to knowledge sheets.
11. A knowledge base system according to claim 10, wherein said knowledge base building apparatus comprising display means for displaying the knowledge sheets in the form of a tree with reference to the scenario and the alternative solution.