- From: Ivan Herman <ivan@w3.org>
- Date: Thu, 03 Jul 2008 17:34:10 +0200
- To: Ivan Herman <ivan@w3.org>, public-powderwg@w3.org
- Message-ID: <486CF172.8060108@w3.org>
I must admit I did not remember that nuance, ie, that hasValue guarantees the existence of one triple. You are absolutely right. Bottomline: I hereby withdraw that comment... Ivan Stasinos Konstantopoulos wrote: > Ivan, hi again. > > On Thu Jul 3 15:36:00 2008 Ivan Herman said: > >> Comment on http://www.w3.org/TR/2008/WD-powder-dr-20080630/ >> >> Looking at examples 2.2 and 2.3 and the way it is translated into >> POWDER-S: the translation is an intersection of restrictions: >> >> <owl:Class rdf:nodeID="descriptorset_1"> >> 27 <owl:intersectionOf rdf:parseType="Collection"> >> 28 <owl:Restriction> >> 29 <owl:onProperty rdf:resource="http://example.org/vocab#color" /> >> 30 <owl:hasValue>red</owl:hasValue> >> 31 </owl:Restriction> >> 32 <owl:Restriction> >> 33 <owl:onProperty rdf:resource="http://example.org/vocab#shape" /> >> 34 <owl:hasValue>square</owl:hasValue> >> 35 </owl:Restriction> >> 36 </owl:intersectionOf> >> 37 <dc:description>Everything on example.org is red and >> square</dc:description> >> 38 <foaf:depiction rdf:resource="http://example.org/icon.png" /> >> 39 </owl:Class> >> >> >> what this means, strictly speaking, is that if I take an instance of >> that class, the 'color' or 'shape' properties will take that specified >> values _if they are applied_. However, it does _not_ say that this >> property _is_ applied on those instances. If the intention of the spec >> is to say 'this and this property _is_ applied and it has this and this >> value', then an extra cardinality restriction for each of those >> properties might be necessary... It is up to the group to decide what >> the intention is, though. > > This would be the case with owl:allValuesFrom. owl:hasValue guarantees > the existence of at least one triple relating the resource with the > value: > > hasValue allows us to specify classes based on the existence of > particular property values. Hence, an individual will be a member of > such a class whenever at least one of its property values is equal to > the hasValue resource. > > http://www.w3.org/TR/2004/REC-owl-guide-20040210/#hasValue > > Empirical verification: the attached exIvan.owl returns: > > Query Results (11 answers): > r | y > ========================================= > ontology:tag | "tag2"^^xsd:string > ontology:tag | "my tag3"^^xsd:string > ontology:tag | "tag1"^^xsd:string > ontology:cp-1.1 | "1"^^xsd:int > ontology:cp-1.2 | "1"^^xsd:int > rdf:type | ontology:Class1 > rdf:type | owl:Thing > rdf:type | ontology:Resource > rdf:type | ontology:Class2 > owl:sameAs | ontology:website2 > owl:differentFrom | ontology:website1 > > when queried > > SELECT ?r ?y WHERE { <http://www.test.org/ontology.owl#website2> ?r ?y } > > cheers, > s > -- Ivan Herman, W3C Semantic Web Activity Lead Home: http://www.w3.org/People/Ivan/ PGP Key: http://www.ivan-herman.net/pgpkey.html FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Thursday, 3 July 2008 15:34:46 UTC