• OWL Features Supported by ELK
• Supported OWL constructs
• Supported syntactic forms
• Corresponding description logic expressivity

OWL Features Supported by ELK

ELK currently supports a subset of the light-weight OWL EL ontology language that is documented on this page. It is intended to support all of OWL EL in upcoming versions of ELK.

Supported OWL constructs

The following constructs of the OWL ontology language are supported in ELK 0.2.0.

Axiom types:

• SubClassOf
• EquivalentClasses
• SubObjectPropertyOf
• EquivalentObjectProperties
• TransitiveObjectProperty
• ObjectPropertyDomain

Class expressions:

• owl:Thing
• ObjectIntersectionOf
• ObjectSomeValuesFrom
• DataHasValue (preliminary support, see below)

Property expressions:

• ObjectPropertyChain

Literal expressions:

• datatype literals in arbitrary datatypes (preliminary support, see below)

Support for data literals in ELK 0.2.0 is still preliminary. In particular, the lexical-value mapping of data literals is not supported, so the equality of values in different syntactic forms is not recognized.

Supported syntactic forms

ELK contains a parser for OWL Functional-Style Syntax, and can read according files from the command line. Ontologies in other formats can be used via the Protégé plugin.

Corresponding description logic expressivity

The semantics of OWL is closely related to that of description logics (DLs); for a first introduction, please see the DL Primer. The above features correspond to the description logic EL+ without ABoxes (and with some preliminary support for concrete roles) which provides the following expressive features.

Concept constructors:

• Top concept
• Concept conjunctions
• Existential (abstract) role restrictions
• Existential restrictions on concrete roles with a nominal value ("dataHasValue"), preliminary support (see above)

Axiom types:

• General concept inclusions (GCIs)
• Role hierarchies (abstract roles)
• Role transitivity and role chains (abstract roles)