Case-based knowledge source for artificial intelligence software shell

An artificial intelligence software shell for plant operation simulation includes a blackboard module including a database having objects representing plant elements and concepts. A rule-based knowledge source module and a case-based knowledge source module, in communication with the blackboard module, operate on specific predefined blackboard objects. The case-based knowledge source module includes cases having past data points on a time scale. Present data is compared with the past data in the cases both on a time scale and on a magnitude scale for determining levels of closeness in time and magnitude. An input data module, in communication with the blackboard module, enables a user to input data to the shell. A control module, in communication with the knowledge source modules and the input data module, receives all input data and controls operation of the knowledge source modules in accordance with a predetermined knowledge source priority scheme.