I actually didn't find the specification to be completely clear in context (language is a funny thing), because it could be read either way without prior knowledge: "is" and "are" can just easily mean "must be" as they could "will become" ? and usually [as a native speaker] one would opt for the former definition.
However, asking around, people tell me RDFS has no concept of constraints at all -- it is all implication.
Given that, I have no objections!
M.
On 2013-Jul-29, at 10:36, V?ctor Rodr?guez Doncel <vrodriguez@fi.upm.es> wrote:
> And I must apologize for my inexperience at writing in mailing lists.
> Do you read me well if I use formatted text? Should I stop using HTML in the mailing list?
>
> Regarding the "rdfs:range", this time the specification is clear:
> http://www.w3.org/TR/rdf-schema/#ch_range
>
> (but one learns it rather with experience).
> The red font in the quotation below is mine (if you manage to read formatted text...).
>
> Regards,
> V?ctor
>
> 3.1 rdfs:range
>
> rdfs:range is an instance of rdf:Property that is used to state that the values of a property are instances of one or more classes.
>
> The triple
>
> P rdfs:range C
>
> states that P is an instance of the class rdf:Property, that C is an instance of the class rdfs:Class and that the resources denoted by the objects of triples whose predicate is P are instances of the class C.
>
>
>
>
>
>
> El 29/07/2013 11:02, Mo McRoberts escribi?:
>> 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.
>>
>>
>
>
> --
> V?ctor Rodr?guez-Doncel
> D3205 - Ontology Engineering Group (OEG)
> Departamento de Inteligencia Artificial
> Facultad de Inform?tica
> Universidad Polit?cnica de Madrid
>
> Campus de Montegancedo s/n
> Boadilla del Monte-28660 Madrid, Spain
> Tel. (+34) 91336 3672
> Skype: vroddon3
>
--
Mo McRoberts - Analyst - BBC Archive Development,
Zone 1.08, BBC Scotland, 40 Pacific Quay, Glasgow G51 1DA,
MC3 D6, Media Centre, 201 Wood Lane, London W12 7TQ,
0141 422 6036 (Internal: 01-26036) - PGP key CEBCF03E
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