Usage Issues
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Usage Issues |
The following usage issue should be noted:
Cardinality of property restrictions
When entering property restrictions in intersectionOf statements of an ontology, the mincardinality and maxcardinality cannot be entered on a single restriction; they must be entered on two separate restrictions for that property.
Otherwise, cardinality is entered as follows:
| 1. | Create a restriction on the subclass of a class, say, by right-clicking the subclass icon  . |
| 2. | Select Add Restriction from the context menu. This inserts a restriction box (screenshot below). |
| 3. | Select or type in the name of the object property to be restricted (screenshot below). |
| 4. | Enter the mincardinality by double-clicking to the left of the two dots below the restriction box (see screenshot above). |
| 5. | Enter the maxcardinality by double-clicking to the right of the two dots below the restriction box (see screenshot above). |
The owl:imports statement in an ontology header (see code fragment below) references a resource on the web or on a local system.
<owl:Ontology rdf:about="">
<owl:versionInfo>v 1.17 2003/02/26 12:56:51 mdean</owl:versionInfo>
<rdfs:comment>An example ontology</rdfs:comment>
<owl:imports rdf:resource="http://www.altova.com/ontologies"/>
</owl:Ontology>
If you are connected to the Internet and there is an ontology at the location indicated by the URI, then this ontology is imported. If you are not connected to the Internet or there is no ontology resource at the location indicated by the URI, SemanticWorks uses the mechanism explained below to locate and import ontology resources.
| 1. | The URI in the owl:imports statement must be the same as the value of the xml:base attribute of the rdf:RDF element of the ontology to be imported. For example, the importing ontology could have the following statement: <owl:imports rdf:resource="http://www.altova.com/ontologies/documents.rdf"/>. The URI declared in the owl:imports statement must match the base URI of the ontology to be imported. This means that there must either be an ontology at the location specified by the URI, or the xml:base attribute of the ontology to be imported must be the same as the owl:imports URI. The document element of the ontology to be imported would need to be: <rdf:RDF xml:base="http://www.altova.com/ontologies/documents.rdf" ...>. |
| 2. | Additionally, the importing ontology must map, using the Namespace Imports for RDF feature, the URI used in the owl:imports statement to the actual (absolute path) location of the imported ontology. |
Also see Base URI and Namespace Imports for RDF for related information.
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