- OWL can be used for simple inferences
- Applications may require other type of rules, e.g.:
						- (prem-1 ∧ prem-2 ∧ …) ⇒ (concl-1  ∧ concl-2  ∧ …)
            
- e.g.: for any «X», «Y» and «Z»:
- “if «Y» is a parent of «X», and «Z» is a brother of «Y» then «Z» is the uncle of «X»”
- “if «Y» is a parent of «X», and «Z» is a brother of «Y» 
- then «Z» is the uncle of «X»”
- using a logic formalism:
- 
              ∀x,z: ((∃y: (y parent x) ∧ (y brother z)) ⇒ (z uncle x))
            
- (Horn clauses)
 
- Lots of research is happening to extend RDF/OWL
- 
					(RuleML,
          SWRL,
          cwm, …)
- W3C may initiate a standardization work in this area, too
						- question is whether results are “ripe” for standardization
							
- and whether the necessary manpower is available