A rule processing apparatus includes modules for defining/entering attributes, enumerations, and/or relationships; packaging the definitions in a reduced canonical form suitable for propositional logic manipulation using zero-suppressed binary decision diagrams (Zdd) to produce a prime Zdd; and/or (iii) executing the rule by applying a series of user inputs to the prime Zdd to determine a result that preferably includes conflict and selection advice to guide the user to satisfaction. Elective events, such as but not limited to the display of messages or the performance of calculations, may optionally be packaged along with the prime rule or components thereof, and presented during execution to help guide the end user to satisfaction or compliancy when choosing among possible selections. The apparatus automates determination of a complex rule having a combinatorial exploded number of rule components, or a combinatorial number of possible outcomes, exceeding computational capacity of present day computing systems.