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OWL 1.1 extends the W3C OWL Web Ontology Language with a small but useful set of features that have been requested by users, for which effective reasoning algorithms are now available, and that OWL tool developers are willing to support. The new features include extra syntactic sugar, additional property and qualified cardinality constructors, extended datatype support, simple metamodelling, and extended annotations. This document provides a high-level overview of these features.
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The initial design of the W3C OWL Web Ontology Language (OWL) was conservative in several ways. Constructs that did not have considerable support from within the W3C Web Ontology Working Group were not included. Constructs for which effective reasoning methods were not known or expected to be known in future were also not included.
Usage of OWL, particularly the OWL DL species of OWL, has identified several constructs that are of considerable utility and that fit well within the representation philosophy of OWL DL. Advances in the theory of Description Logics have provided a basis for reasoning with constructs that are not part of OWL, or not part of OWL DL.
For both these reasons, it was decided at the first OWL: Experiences and Directions workshop to design an extension to the OWL DL species of OWL. The extension is designed to provide simple extensions to OWL DL that
This document provides a high-level overview of OWL 1.1. The OWL 1.1 syntax document [OWL 1.1 Syntax] defines the normal syntax for OWL 1.1 and give some informal information on the semantics of the new constructs. There will be an OWL 1.1 semantics document that formally defines the semantics of all of OWL 1.1, but the general intent is that the semantics of OWL 1.1 is the same as that of [SROIQ]. with a simple datatype theory.
The features added in OWL 1.1 fall into four main categories:
OWL 1.1 provides two constructs that are simply syntactic sugar, to make some common idioms easier to write.
The first syntactic sugar construct, DisjointUnion, defines one description as the disjoint union of a set of descriptions. It is simply a combination of a DisjointClasses axiom and an EquivalentClasses axiom of the first description as the union of the rest.
The second syntactic sugar construct is negative property membership assertions NegativeObjectPropertyAssertion and NegativeDataPropertyAssertion.
OWL 1.1 provides extra Description Logic expressive power, moving from the SHOIN Description Logic that underlies OWL DL to the SROIQ Description Logic. The additions are:
OWL 1.1 allows user-defined datatypes, using a mechanism similar to that in Protege. User-defined datatypes can use most of the well-behaved datatype facets available from [XML Schema Datatypes].
This facility can be used in defining new datatypes that can be used in the ontology, as in SubClassOf(Adult DataSomeValuesFrom(age DatatypeRestriction(xsd:integer 1 minInclusive "18"^^xsd:integer)).
Simple relationships between values of functional data-valued properties can be used as restrictions, as in DataSomeValuesFrom(shoeSize IQ greaterThan). The underlying theory of datatypes used in these restrictions is taken from [XML Schema Datatypes].
In OWL 1.1 a name (such as Person) can be used as any or all of an individual, a class, or a property. The computational problems that would arise if this were treated as in RDF are avoided by ensuring that no aspect of the use of the name as an individual has any effect on the meaning of the name as a class. Such a treatment of metamodeling is often called punning.