On 2013-Jul-29, at 09:50, V?ctor Rodr?guez Doncel <vrodriguez@fi.upm.es>
wrote:
>
> My answer below...
>
> El 27/07/2013 9:51, Mo McRoberts escribi?:
>> On 26 Jul 2013, at 14:36, V?ctor Rodr?guez Doncel <vrodriguez@fi.upm.es>
>> wrote:
>>
>>
>>> Well, of course Asset must exist. But your sentence...
>>> The act of associating a policy with it is what defines it as an ODRL asset.
>>> ...can be represented very simply and elegantly, with just three statements:
>>>
>>> <Asset> rdf:type owl:Class .
>>> <vocab:target> rdf:type owl:ObjectProperty ;
>>> rdfs:range <Asset> .
>>>
>>> Everything that is related to with a "vocab:target" is automatically inferred to be an Asset.
>>>
>> That does not infer that, though, does it?
>>
> Yes, it does :)
>> That says that everything related with vocab:target *must be defined as* an Asset; to specify a vocab:target being an instance which was not explicitly stated as being an Asset would be a violation of the schema.
>>
> No, it isn't :) . Whatever it is, the instance will be classified as an Asset. Without you to declare it, without clashing with your previous class declarations.
I must confess I'm not entirely understanding that: how does specifying that the range of vocab:target cause that inference? Isn't a range a constraint, rather than an implication?
>>> Or even more exactly:
>>>
>>> <Asset> rdf:type owl:Class ;
>>> owl:equivalentClass [ rdf:type owl:Restriction ;
>>> owl:onProperty [ owl:inverseOf <vocab:target> ] ;
>>> owl:someValuesFrom owl:Thing
>>> ] .
>>>
>>> Which can be read: "Everything that is range of a vocab:target, and only what is in range of a vocab:target, is an Asset".
>>> At your choice.
>>>
> This alternative declares that Assets are only such if bound through the vocab:target. I'd say this is over-restrictive and we don't need this.
Hm, as above: I don't quite follow how declaring a *restriction* brings about an *implication*?
I'll cheerfully confess I'm no OWL guru, but I'd like to get my head around how this works!
M.
--
Mo McRoberts - Analyst - BBC Archive Development,
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