An intelligent control shell for CAD tools

Describes an intelligent control shell for CAD tools, which can automatically create a command sequence to control CAD systems using symbolic knowledge of general command flows and non-symbolic knowledge of the past execution data. Users define a model of possible control flows, which are transformed into a state transition graph from which executable command sequences are inferred. The control system statistically analyzes non-deterministic branches, where a final result is predicted from a current state of a design object, a command history and the succeeding commands. Then the most promising command to optimize the design objects is selected and executed. The LSI CAD system controlled by the proposed shell synthesizes circuits about 5% faster than that synthesized with a standard script for delay minimization. >