RuleML is a modular, webized Rule Markup & Modeling Language based on XML and RDF, developed by the Rule Markup Initiative.
Relevance
Part of the modular family of RuleML sublanguages http://www.ruleml.org/modularization/#Model has been used in the Rulesystem Arrangement Framework section on "Phase 1 Expressive Discriminators".
Versions of the RuleML XML serialization have been used in all the rule submissions:
FOL RuleML, a part of the Semantic Web Rule Language First-Order Logic (SWRL FOL)
Semantic Web Services Language (SWSL), a part of the Semantic Web Services Framework (SWSF)
The Horn logic sublanguage of RuleML has been realized with rule engines such as the reference implementation OO jDREW, which can be developed into a RIF RuleML engine.
Translators (in XSLT and Java) between RuleML and other languages such as Prolog and Jess have been developed to support rule-system interoperation http://www.ruleml.org/#Translators.
Numerous RuleML use cases have been developed, some of which being described in the collection of RIF Use Cases:
Frame-based representation, Inheritance of defaults, Reification
E-Procurement Contract Exchange, with Default-Inheritance Ontologies
Rule Based Service Level Management and SLAs for Service Oriented Computing
Rule Interchange Through Test-Driven Verification and Validation
Representing some levels of fuzzy rules with the help of datatype built-ins
Impact on Design
For Phase 1, the modular RuleML design and its XSDs http://www.ruleml.org/spec can be adapted and further developed, mainly http://www.ruleml.org/0.9/xsd/hornlog.xsd and nearby sublanguage modules.
For Phase 2, classical Negation and Negation-As-Failure can be made available in separate sublanguages and in a combined one, as exemplified inside the Negation Datalog module http://www.ruleml.org/modularization/#Model. Various fragments of OWL can be -- homogeneous approach -- in subsets of SWRL http://www.w3.org/Submission/2004/SUBM-SWRL-20040521 or become -- heterogeneous approach -- DL queries in hybrid rules http://www.jdrew.org/oojdrew/exa/hybridrules.html.
For More Information
The RuleML Initiative http://www.ruleml.org and Conferences (http://2005.ruleml.org, http://2006.ruleml.org) have provided continuing expertise and exchange in the area of web rules. Also see the Charter entry http://www.w3.org/2005/rules/wg/charter#ruleml.