[Semantic Web]Layering of OWL

读书笔记 Lee 发表于 2006/3/3 23:00:20 Now that we have discussed all the language constructors of OWL, we can completely specify which features of the language may be used in which sublanguage (OWL Full, OWL or OWL Lite).   OWL Full In OWL Full, all the language constructors may be used in any combination as long as the result is legal RDF. OWL DL In order to exploit the formal underpinnings and computational tractability of Description Logics, the following constraints must be obeyed in an OWL DL ontology: • Vocabulary partitioning. Any resource is allowed to be only a class, a data type, a data type property, an object property, an individual, a data value, or part of the built-in vocabulary, and not more than one of these. This means that, for example, a class cannot at the same time be an individual, or that a property cannot have some values from a data type and some values from a class (this would make it both a data type property and an object property). • Explicit typing. Not only must all resources be partitioned (as prescribed in the previous constraint) but this partitioning must be stated explicitly. For example, if an ontology contains the following: <owl:Class rdf:ID="C1"> <rdfs:subClassOf rdf:about="#C2" /> </owl:Class> this already entails that C2 is a class (by virtue of the range specification of rdfs:subClassOf). Nevertheless, an OWL DL ontology must explicitly state this information: <owl:Class rdf:ID="C2"/> • Property separation. By virtue of the first constraint, the set of object properties and data type properties are disjoint. This implies that the following can never be specified for data type properties: owl:inverseOf, owl:FunctionalProperty, owl:InverseFunctionalProperty, and owl:SymmetricProperty. • No transitive cardinality restrictions. No cardinality restrictions may be placed on transitive properties (or their subproperties, which are of course also transitive, by implication). • Restricted anonymous classes. Anonymous classes are only allowed to occur as the domain and range of either owl :equivalentClass or owl:disjointWith, and as the range (but not the domain) of rdfs:subClassOf. OWL Lite An OWL Lite ontology must be an OWL DL ontology and must further satisfy the following constraints: • The constructors owl:oneOf, owl:disjointWith, owl:unionOf, owl:complementOf and owl:hasValue are not allowed. • Cardinality statements ( minimal, maximal, and exact cardinality) can only bemade on the values 0 or 1 and no longer on arbitrary non-negative integers.• owl:equivalentClass statements can no longer be made between anonymous classes but only between class identifiers.

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