W3C home > Mailing lists > Public > public-powderwg@w3.org > April 2008

Re: Another semantics question

From: Stasinos Konstantopoulos <konstant@iit.demokritos.gr>
Date: Wed, 23 Apr 2008 00:52:44 +0300
To: Phil Archer <parcher@icra.org>
Cc: Public POWDER <public-powderwg@w3.org>
Message-ID: <20080422215243.GA5492@iit.demokritos.gr>

On Tue Apr 22 10:19:11 2008 Phil Archer said:

> What's the difference between these two
> <owl:Restriction>
>   <owl:onProperty
>     rdf:resource="http://www.w3.org/2007/05/powder#hasIRI"/>
>   <owl:someValuesFrom rdf:nodeID="iriset_1"/>
>   <rdfs:subClassOf rdf:nodeID="descriptorset_1"/>
> </owl:Restriction>

this one means:
all resources that have a hasIRI property that has a value from
"iriset_1" are also in the "descriptorset_1" class.

> <owl:Class rdf:about="#resourceset_1">
>   <rdfs:subClassOf rdf:ID="description_1"/>
> </owl:Class>

all resources in "resourceset_1" are also in "description_1"

> and which should we use?

It's hard to tell in isolation, depends on where "resourceset_1" comes
from. If it is defined as a restriction on a property, then these two
might as well mean the same.

> is this about necessary and necessary and sufficient?

No, they are both asserting one-way implications. If one wants to say
"necessary and sufficient", in other words, not just *a* way to be
in "descriptorset_1", but *the only* way to be in "descriptorset_1",
then rdfs:subClassOf must be replaced by owl:equivalentClass

Received on Tuesday, 22 April 2008 21:53:25 UTC

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