The RACER system (Renamed ABox and Concept Expression Reasoner) is a knowledge representation system that implements a highly optimized tableau calculus for a very expressive description logic. It offers reasoning services for multiple TBoxes and for multiple ABoxes as well. The system implements the description logic (see ALCQHI ) also known as (see SHIQ ). This is the basic logic (see ALC (logic) ) augmented with qualifying number restrictions, role hierarchies , inverse roles , and transitive roles . In addition to these basic features, RACER also provides facilities for algebraic reasoning including concrete domains for dealing with:

• min/max restrictions over the integers,
• linear polynomial (in-)equations over the reals or cardinals with order relations ,
• nonlinear multivariate polynomial (in-)equations over complex numbers,
• equalities and inequalities of strings.

RACER supports the specification of general terminological axioms. A TBox may contain general concept inclusions (GCIs), which state the subsumption relation between two concept terms . Multiple definitions or even cyclic definitions of concepts can be handled by RACER.

RACER implements the HTTP-based quasi-standard DIG for interconnecting DL systems with interfaces and applications using an XML-based protocol. RACER also implements most of the functions specified in the older Knowledge Representation System Specification (KRSS ).

RACER has been initially developed at the University of Hamburg, Germany. RACER is actively supported and future releases are developed at Concordia University in Montreal, Canada, and at the University of Applied Sciences in Wedel near Hamburg, Germany.

See also

• Semantic Web
• Description logic
• Ontology (computer science)
• DAML, OIL and DAML+OIL
• OWL

References

• http://www.sts.tu-harburg.de/~r.f.moeller/racer/racer-manual-1-7-19.pdf

External links

• http://www.sts.tu-harburg.de/~r.f.moeller/racer/