Web Ontology Language: OWL The disadvantage of OWL Full is the language has become so powerful as to be undecidable, dashing any hope of complete (let alone efficient) reason OWL DL: In order to regain computational efficiency, OWL DL(short for: Description Logic)is a sublanguage of OWL Full which restricts the way in which the constructors from OWL and RDF can be used. We will give details later, but roughly this amounts to disallowing application of OWLs constructor's to each other, and thus ensuring that the language corresponds to a well studied description logic. The advantage of this is that it permits efficient reasoning support The disadvantage is that we loose full compatibility with RDF: an RDF document will in general have to be extended in some ways and restricted in others before it is a legal OWL DL document. Conversely, every legal OWL DL document is still a legal rdF document OwL Lite: An ever further restriction limits oWl dl to a subset of the language constructors. For example, OWL Lite excludes enumerated classes, disjointness statements and arbitrary cardinality(among others) The advantage of this is a language that is both easier to grasp(for users) and easier to implement(for tool builders) The disadvantage is of course a restricted expressivity. Ontology developers adopting OWL should consider which sublanguage best suits their needs. The choice between OwL Lite and OWL Dl depends on the extent to which users require the more-expressive constructs provided by OWL DL and OWL Full. The choice between OWL DL and OWl Full mainly depends on the extent to which users require the meta-modeling facilities of RDF Schema (e.g. defining classes of classes, or attaching properties to classes). When using OWL Full as compared to OWL DL, reasoning support is less predictable since complete OWl Full implementations will be imposs There are strict notions of upward compatibility between these three sub- Every legal Owl Lite ontology is a legal oWL dl ontology. Every legal OWL DL ontology is a legal OWL Full ontology. Every valid OWl Lite conclusion is a valid OWL DL conclusion Every valid OWL DL conclusion is a valid OWL Full conclus OWL still uses RDF and RDF Schema to a large extent all varieties of OWL use RDF for their syntax instances are declared as in RDF, using rdF descriptions and typing OWL constructors like owl: Class, owl: DatatypeProperty and owl: ObjectProperty are all specialisations of their RDF counterparts Figure 1 shows the subclass relationships between some modelling primi- tives of owl and RDF/ RDFSWeb Ontology Language: OWL 5 The disadvantage of OWL Full is the language has become so powerful as to be undecidable, dashing any hope of complete (let alone efficient) reasoning support. • OWL DL: In order to regain computational efficiency, OWL DL (short for: Description Logic) is a sublanguage of OWL Full which restricts the way in which the constructors from OWL and RDF can be used. We will give details later, but roughly this amounts to disallowing application of OWL’s constructor’s to each other, and thus ensuring that the language corresponds to a well studied description logic. The advantage of this is that it permits efficient reasoning support. The disadvantage is that we loose full compatibility with RDF: an RDF document will in general have to be extended in some ways and restricted in others before it is a legal OWL DL document. Conversely, every legal OWL DL document is still a legal RDF document. • OWL Lite: An ever further restriction limits OWL DL to a subset of the language constructors. For example, OWL Lite excludes enumerated classes, disjointness statements and arbitrary cardinality (among others). The advantage of this is a language that is both easier to grasp (for users) and easier to implement (for tool builders). The disadvantage is of course a restricted expressivity. Ontology developers adopting OWL should consider which sublanguage best suits their needs. The choice between OWL Lite and OWL DL depends on the extent to which users require the more-expressive constructs provided by OWL DL and OWL Full. The choice between OWL DL and OWL Full mainly depends on the extent to which users require the meta-modeling facilities of RDF Schema (e.g. defining classes of classes, or attaching properties to classes). When using OWL Full as compared to OWL DL, reasoning support is less predictable since complete OWL Full implementations will be impossible. There are strict notions of upward compatibility between these three sub￾languages: • Every legal OWL Lite ontology is a legal OWL DL ontology. • Every legal OWL DL ontology is a legal OWL Full ontology. • Every valid OWL Lite conclusion is a valid OWL DL conclusion. • Every valid OWL DL conclusion is a valid OWL Full conclusion. OWL still uses RDF and RDF Schema to a large extent: • all varieties of OWL use RDF for their syntax • instances are declared as in RDF, using RDF descriptions and typing in￾formation • OWL constructors like owl:Class, owl:DatatypeProperty and owl:ObjectProperty are all specialisations of their RDF counterparts. Figure 1 shows the subclass relationships between some modelling primi￾tives of OWL and RDF/RDFS