Bubo---Implementing OWL in Rule-Based Systems

Volz, Decker, Oberle

owl semantic web rule-based programming logic declarative production systems

@inproceedings{volz:WWW-2003,
  title={{Bubo}---Implementing {OWL} in Rule-Based Systems},
  author={Raphael Volz and Stefan Decker and Daniel Oberle},
  booktitle={International World Wide Web Conference ({WWW})},
  month={May},
  year={2003}

OWL has strong support for conceptualization queries

Less support for working with instance data

• Not even as expressive as conjunctive queries, which nearly all DBs support

RuleML operates on the data layer only, not over the ontology layer

Binary representation (predicate(subject, object)) is generally faster than triple representation (triple(predicate, subject, object))

• This work also creates unary relations for type assertions (type(subject, object) -> object(subject))

Itemizes translations of OWL constructs to horn clauses

• Including various discussion about equality

Discusses supporting terminological queries by proposing candidate instances and checking what comes out

• I.e., to see if C is a subclass of D, propose an instance of C and check if it is inferred to be an instance of D

Datalog for deductive database imposes two additional restrictions

• Range restriction: All variables in consequent must be present in antecedent
• Function symbols with arity > 0 are not allowed
• These place some limits on the logic supported, namely cardinatily constructs

Sideways information passing

Implementation in RDBMS

• Recursion is particularly tricky

Misstates several properties & is not complete, despite claims