NxBRE is a lightweight Business Rule Engine (aka Rule Based Engine) for the .NET platform, composed of a forward-chaining inference engine and an XML-driven flow control engine. It supports RuleML 0.9 Naf Datalog and Visio 2003 modeling.
Atoms can be used in different implications in Visio 2003
Editing rules in Visio 2003
The Inference Engine Console helps twiddling rule bases