"SweetRules is a pluggable set of rules tools for RuleML and SWRL featuring: interoperability between Prolog, production rules, OWL, CommonRules, Jena-2, and several other languages; and inferencing with negation, priorities, and procedural attachments." [https://ebiquity.umbc.edu/project/html/id/60/SweetRules]
Benjamin Grosof project
Applied to computable contracts as SweetDeal