OWL 1.1 Web Ontology Language:
Mapping to RDF Graphs

W3C Working Draft 8 January 2008

This version:

http://www.w3.org/TR/2008/WD-owl11-mapping-to-rdf-20080108/

Latest version:

http://www.w3.org/TR/owl11-mapping-to-rdf/

Authors:

Bernardo Cuenca Grau, Oxford University

Boris Motik, Oxford University

Contributors:

Ian Horrocks, Oxford University

Bijan Parsia, The University of Manchester

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Copyright © 2008 W3C^® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.

Abstract

Status of this Document

May Be Superseded

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

Set of Documents

This document is being published as one of a set of 3 documents:

1. Structural Specification and Functional-Style Syntax
2. Model-Theoretic Semantics
3. Mapping to RDF Graphs (this document)

Ongoing Changes

These First Public Working Drafts are based closely on the OWL 1.1 Submission, a set of documents developed outside of W3C as proposed refinements and extensions to the W3C's 2004 OWL Recommendation.

A number of features of OWL 1.1 are still under consideration by the OWL Working Group. Future versions of these documents may modify or drop descriptions of some features, or add specification of new features. Where specific issues have been identified on which the Working Group intends to make a decision, relevant parts of this document have been labeled with an "Editor's Note". Although the WG aims to maximise backwards compatibility with OWL 1.0, such compatibility cannot be guaranteed in all cases. The Working Group is publishing these drafts for public comment in order to inform the ongoing decision making process.

Please Comment By 19 February 2008

The OWL Working Group seeks public feedback on these Working Drafts. Please send your comments to public-owl-comments@w3.org (public archive). If possible, please offer specific changes to the text that would address your concern.

No Endorsement

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

Patents

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Editor's Note: See Issue-66 (mapping inconsistencies).

This document provides a mapping from the functional-style syntax of OWL 1.1 as given in [OWL 1.1 Specification] to the RDF exchange syntax for OWL 1.1 and vice versa. Every OWL 1.1 ontology can be serialized in RDF, so every OWL 1.1 ontology in RDF is a valid OWL Full ontology. The RDF syntax of OWL 1.1 is backwards-compatible with OWL DL, this is, every OWL DL ontology in RDF is a valid OWL 1.1 ontology. The semantics OWL 1.1 is defined for ontologies in the functional-style syntax. OWL 1.1 ontologies serialized in RDF/XML are interpreted by translating them into the functional-style syntax and applying the OWL 1.1 semantics [OWL 1.1 Semantics]. The syntax for triples used here is the one used in the RDF Semantics document. Full URIs are abbreviated using namespaces as usual.

Editor's Note: The actual namespaces used in the specification are subject to discussion and might change in future.

The following notation is used throughout this document:

• _:x denotes a blank node;
• x denotes a blank or a named node;
• !x denotes a named node; and
• T(SEQ y₁ ... y_n) denotes the encoding of an RDF list as shown in Table 1.

Editor's Note: See Issue-2 (allDisjoint-RDF), Issue-68 (nonmonotonic mapping) and Issue-81 (reification, negative assertions).

As explained in [OWL 1.1 Specification], OWL 1.1 syntax is fully typed -- that is, from the syntax, one can immediately see what is the intendend usage of some symbol. OWL 1.0 syntax is not typed; rather, OWL 1.0 relies on explicit statements that determine the type of each URI. For backwards compatibility, OWL 1.1 uses OWL 1.0 vocabulary whenever there is no ambiguity. This is made precise using the following definition.

The type of a symbol S in an ontology O (in functional-style syntax), written Type(S,O), is defined as the smallest set such that

• if the parse tree of O contains S under a objectPropertyURI node, then owl:ObjectProperty ∈ Type(S,O);
• if the parse tree of O contains S under a dataPropertyURI node, then owl:DatatypeProperty ∈ Type(S,O);
• if the parse tree of O contains S under a annotationURI node, then owl:AnnotationProperty ∈ Type(S,O);
• if the parse tree of O contains S under a owlClassURI node, then owl:Class ∈ Type(S,O);
• if the parse tree of O contains S under a datatypeURI node, then rdfs:Datatype ∈ Type(S,O); and
• if the parse tree of O contains S under a individualURI node, then owl11:Individual ∈ Type(S,O).

The above definition refers to a parse tree only for the axioms from O, and not from the axioms from some ontology that O imports. A symbol S in punned in an ontology O if Type(S,O) contains more than one element. Based on that, the following two conditions are defined:

• OnlyOP(S) is true if and only if owl:ObjectProperty ∈ Type(S,O) and owl:DatatypeProperty and owl:AnnotationProperty are not in Type(S,O);
• OnlyDP(S) is true if and only if owl:DatatypeProperty ∈ Type(S,O) and owl:ObjectProperty and owl:AnnotationProperty are not in Type(S,O);
• OnlyAP(S) is true if and only if owl:AnnotationProperty ∈ Type(S,O) and owl:ObjectProperty and owl:DatatypeProperty are not in Type(S,O).

The following shortcuts are used in the translation of OWL 1.1 ontologies into RDF:

• RESTRICTION[op] expands to owl:Restriction if OnlyOP(op) = true, and to owl11:ObjectRestriction otherwise;
• RESTRICTION[dp] expands to owl:Restriction if OnlyDP(dp) = true, and to owl11:DataRestriction otherwise;
• SUBPROPERTYOF[op₁,...,op_n] expands to rdfs:subPropertyOf if OnlyOP(op_i) = true for each 1 ≤ i ≤ n, and to owl11:subObjectPropertyOf otherwise;
• SUBPROPERTYOF[dp₁,dp₂] expands to rdfs:subPropertyOf if OnlyDP(dp₁) = true and OnlyDP(dp₂) = true, and to owl11:subDataPropertyOf otherwise;
• EQUIVALENTPROPERTY[op₁,...,op_n] expands to owl:equivalentProperty if OnlyOP(op_i) = true for each 1 ≤ i ≤ n, and to owl11:equivalentObjectProperty otherwise;
• EQUIVALENTPROPERTY[dp₁,...,dp_n] expands to owl:equivalentProperty if OnlyDP(dp_i) = true for each 1 ≤ i ≤ n, and to owl11:equivalentDataProperty otherwise;
• FUNCTIONALPROPERTY[op] expands to owl:FunctionalProperty if OnlyOP(op) = true, and to owl11:FunctionalObjectProperty otherwise;
• FUNCTIONALPROPERTY[dp] expands to owl:FunctionalProperty if OnlyDP(dp) = true, and to owl11:FunctionalDataProperty otherwise;
• DOMAIN[op] expands to rdfs:domain if OnlyOP(op) = true, and to owl11:objectPropertyDomain otherwise;
• DOMAIN[dp] expands to rdfs:domain if OnlyDP(dp) = true, and to owl11:dataPropertyDomain otherwise;
• RANGE[op] expands to rdfs:range if OnlyOP(op) = true, and to owl11:objectPropertyRange otherwise; and
• RANGE[dp] expands to rdfs:range if OnlyDP(dp) = true, and to owl11:dataPropertyRange otherwise.

Table 2 presents the operator T that translates an OWL 1.1 ontology in functional-style syntax into a set of RDF triples. This table does not consider axioms with annotations: the translation of such axioms is described in Section 2.1.

Editor's Note: See Issue-12 (multi-triple annotations) and Issue-67 (reification).

Axioms with annotations are reified. If s p o is the RDF serialization of the corresponding axiom without annotations given in Table 2 and the axiom contains annotations Annotation(apID_i ct_i), 1 ≤ i ≤ n, then, instead of being serialized as s p o, the axiom is serialized as follows:

_:x rdf:type owl11:Axiom
_:x T(apID_i) T(ct_i) 1 ≤ i ≤ n
_:x rdf:subject s
_:x rdf:predicate p
_:x rdf:object o

Negative object and data property assertions are already reified so only the following triples are added if an assertion contains an annotation:

_:x T(apID_i) T(ct_i) 1 ≤ i ≤ n

Note that the Label and Comment annotations are just abbreviations. They are serialized into RDF triples by expanding the abbreviation and then applying the transformation from Table 2.

[OWL 1.1 Specification]

OWL 1.1 Web Ontology Language: Structural Specification and Functional-Style Syntax Boris Motik, Peter F. Patel-Schneider, Ian Horrocks. W3C Working Draft, 8 January 2008, http://www.w3.org/TR/2008/WD-owl11-syntax-20080108/. Latest version available at http://www.w3.org/TR/owl11-syntax/.

[OWL 1.1 Semantics]

OWL 1.1 Web Ontology Language: Model-Theoretic Semantics Bernardo Cuenca Grau, Boris Motik. W3C Working Draft, 8 January 2008, http://www.w3.org/TR/2008/WD-owl11-semantics-20080108/. Latest version available at http://www.w3.org/TR/owl11-semantics/.

[RDF Semantics]

RDF Semantics. Patrick Hayes, Editor, W3C Recommendation, 10 February 2004, http://www.w3.org/TR/2004/REC-rdf-mt-20040210/.