Conformance-v3

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Document title:
OWL 2 Web Ontology Language
Conformance (Second Edition)

1 Conformance (Normative)

This section uses the words MUST, MUST NOT, SHOULD and MAY as in [RFC 2119].

1.1 Document Conformance

1.1.1 Syntactic Conformance

Any RDF document [RDF Syntax] is an OWL 2 Full ontology document.

An OWL 2 Full ontology document is an OWL 2 DL ontology document iff it can be successfully parsed using the canonical RDF parsing process [OWL 2 Mapping to RDF Graphs] and the resulting ontology in the functional-style syntax satisfies all the restrictions on OWL 2 DL ontologies [OWL 2 Specification].

An OWL 2 DL ontology document is an OWL 2 EL ontology document iff it can be successfully parsed using the canonical RDF parsing process [OWL 2 Mapping to RDF Graphs] and the resulting ontology in the functional-style syntax satisfies all the restrictions on OWL 2 EL ontologies [OWL 2 Profiles].

An OWL 2 DL ontology document is an OWL 2 QL ontology document iff it can be successfully parsed using the canonical RDF parsing process [OWL 2 Mapping to RDF Graphs] and the resulting ontology in the functional-style syntax satisfies all the restrictions on OWL 2 QL ontologies [OWL 2 Profiles].

An OWL 2 Full ontology document is an OWL 2 RL ontology document iff it can be successfully parsed using the canonical RDF parsing process [OWL 2 Mapping to RDF Graphs] and the resulting ontology in the functional-style syntax satisfies all the restrictions on OWL 2 RL ontologies [OWL 2 Profiles].

1.1.2 Semantic Conformance

In OWL 2, semantic conditions are defined with respect to a datatype map [OWL 2 Specification]. This MUST be either an OWL Datatype map [OWL 2 Specification], or and extension of an OWL Datatype map to include additional datatypes.

1.2 Document Checker Conformance

1.2.1 Entailment Checker

An OWL 2 entailment checker takes as input two OWL 2 ontology documents O1 and O2 and checks if O1 entails O2 with respect to a datatype map and either the Model-Theoretic Semantics [OWL 2 Semantics] or the RDF-Based Semantics [OWL 2 RDF-Based Semantics]. Additionally:

  • It MUST provide a means to determine the datatypes supported by its datatype map [OWL 2 Specification]; for example, by listing them in its supporting documentation.
  • It MUST provide a means to determine the semantics it uses (either the Model-Theoretic Semantics [OWL 2 Semantics] or the RDF-Based Semantics [OWL 2 RDF-Based Semantics]); for example, in its supporting documentation.

An OWL 2 entailment checker returns a single result, being True, False, or Unknown. Additionally:

  • It MUST report an error if the parsing process fails (for example, due to network errors).
  • It MUST report an error if an input document uses datatypes that are not supported by its datatype map or literals that it does not support (for example, very large integers).
  • It SHOULD NOT return Unknown. While sometimes needed (for example, for pragmatic reasons), Unknown is not a desired response.

Five different conformance classes of OWL entailment checker are defined:

An OWL 2 Full entailment checker is an OWL 2 entailment checker that takes RDF documents as input, and uses the RDF-Based Semantics [OWL 2 RDF-Based Semantics]; it MUST return True only when O1 entails O2, and it must return False only when O1 does not entail O2.

An OWL 2 DL entailment checker is an OWL 2 entailment checker that takes OWL 2 DL ontology documents as input, and uses the Model Theoretic Semantics [OWL 2 Semantics]; it MUST return True only when O1 entails O2, and it must return False only when O1 does not entail O2.

An OWL 2 EL entailment checker is an OWL 2 entailment checker that takes OWL 2 EL ontology documents as input, and uses the Model Theoretic Semantics [OWL 2 Semantics]; it MUST return True only when O1 entails O2, and it must return False only when O1 does not entail O2.

An OWL 2 QL entailment checker is an OWL 2 entailment checker that takes OWL 2 QL ontology documents as input, and uses the Model Theoretic Semantics [OWL 2 Semantics]; it MUST return True only when O1 entails O2, and it must return False only when O1 does not entail O2.

An OWL 2 RL entailment checker is an OWL 2 entailment checker that takes RDF documents as input, and uses the RDF-Based Semantics [OWL 2 RDF-Based Semantics]; it MUST return True only when O1 entails O2, and it must return False only when FO(O1)R does not entail FO(O2) under the standard first-order semantics, where R denotes the OWL 2 RL/RDF rules [OWL 2 Profiles], and FO(O) denotes the FO theory corresponding to O in which triples are represented using the T predicate — that is, T(s, p, o) represents an RDF triple with the subject s, predicate p, and the object o. An OWL 2 RL entailment checker MAY report a warning unless O1 and O2 satisfy the constraints described in Theorem 1 of Profiles [OWL 2 Profiles].

An OWL 2 entailment checker is terminating if, given sufficient memory resources, it will always either reject the input as syntactically invalid, or return True, False, or Unknown in a finite amount of time (i.e., CPU cycles).

An OWL 2 entailment checker is complete if, given sufficient CPU and memory resources, it will always either reject the input as syntactically invalid, or return True or False.

Note: Every OWL 2 Full entailment checker is also an OWL 2 RL entailment checker.

Note: Every OWL 2 DL entailment checker is also an OWL 2 EL and OWL 2 QL entailment checker.

Note: A complete and terminating consistency checker MAY return Unknown in the case where a resource limit has been exceeded.

2 References

[OWL 2 Specification]
OWL 2 Web Ontology Language: Structural Specification and Functional-Style Syntax. Peter F. Patel-Schneider, Ian Horrocks, and Boris Motik, eds., 2008.
[OWL 2 Semantics]
OWL 2 Web Ontology Language: Model-Theoretic Semantics. Bernardo Cuenca Grau and Boris Motik, eds., 2008.
[OWL 2 RDF-Based Semantics]
OWL 2 Web Ontology Language: RDF-Based Semantics. Michael Schneider, 2008.
[OWL 2 Profiles]
OWL 2 Web Ontology Language: Profiles. Bernardo Cuenca Grau, Boris Motik, Zhe Wu, Achille Fokoue and Carsten Lutz, 2008.
[RDF Syntax]
RDF/XML Syntax Specification (Revised). Dave Beckett, Editor, W3C Recommendation 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/ . Latest version available at http://www.w3.org/TR/rdf-syntax-grammar/ .
[SROIQ]
The Even More Irresistible SROIQ. Ian Horrocks, Oliver Kutz, and Uli Sattler. In Proc. of the 10th Int. Conf. on Principles of Knowledge Representation and Reasoning (KR 2006). AAAI Press, 2006.
[OWL Metamodeling]
On the Properties of Metamodeling in OWL. Boris Motik. Journal of Logic and Computation, 17(4):617-637, 2007.