Re: Official OWL version outdated

I think a unionOf expression for the list of classes in schema:domain and schema:range would be a quite correct OWL representation of the original schema.org meta-model, same as in GoodRelations:

foo:property a owl:ObjectProperty;
	rdfs:domain [ a owl:Class;
		      owl:unionOf (foo:Class1 foo:Class2 foo:Class3) ]. 

The same work for owl:DatatypeProperty, too, of course.

This is how GoodRelations has always been handling domain and range in OWL; it avoids unintended class membership inferences yet still provides guidance on which classes are compatible with a property.



On May 14, 2013, at 12:15 AM, Holger Knublauch wrote:

> Hi Bernard,
> 
> the goal of my schema.org version was to be as friendly as possible to existing OWL/RDF tools. These existing tools have no idea what the properties schema:domain or schema:domainIncludes mean. Therefore I am using rdfs:domain. The topbraid version is not intended to be a 1:1 mapping of the official schema.org RDFa version - that already exists and people can use it if they prefer. I have left the schema:domain/range triples in my OWL version so that tools can consult those in addition to the rdfs: properties.
> 
> Note that it's a different topic whether something like schema:domainIncludes should be standardized and used more widely - I agree that these might be more intuitive and extensible than the OWL work-around of owl:unionOf. But that's a larger topic...
> 
> Regards,
> Holger
> 
> 
> On 5/14/2013 2:00, Bernard Vatant wrote:
>> Hi Holger
>> 
>> Nice try :)
>> 
>> I have comments on the redundant use of rdfs:domain, schema:domain. rdfs:range, schema:range.
>> As explained quite a while ago by Dan and others, the way schema.org binds properties to classes is over-specified by rdfs:domain and rdfs:range, that's why the RDFa expression uses schema:domain and schema:range instead, 
>> But actually those properties themselves are not defined, but schema:domainIncludes and schema:rangeIncludes are defined.
>> 
>> So, seems to me all redundant declarations of rdfs:domain and schema:domain should be replaced by a single schema:domainIncludes, and all redundant declarations of rdfs:range and schema:range should be replaced by a single schema:rangeIncludes.
>> 
>> For example instead of ...
>> <owl:ObjectProperty rdf:about="http://schema.org/editor">
>>     <rdfs:range rdf:resource="http://schema.org/Person"/>
>>     <rdfs:domain rdf:resource="http://schema.org/CreativeWork"/>
>>     <schema:range rdf:resource="http://schema.org/Person"/>
>>     <schema:domain rdf:resource="http://schema.org/CreativeWork"/>
>> </owl:ObjectProperty>
>> declare the following ...
>> <owl:ObjectProperty rdf:about="http://schema.org/editor">
>>     <schema:rangeIncludes rdf:resource="http://schema.org/Person"/>
>>     <schema:domainIncludes rdf:resource="http://schema.org/CreativeWork"/>
>> </owl:ObjectProperty>
>> 
>> 
>> 2013/5/11 Holger Knublauch <holger@topquadrant.com>
>> I have posted an up to date OWL version of schema.org at
>> 
>>     http://topbraid.org/schema/
>> 
>> which follows different OWL encoding conventions than the other RDF/OWL version(s) that I have come across. The page above explains these conventions and their motivation.
>> 
>> Feedback appreciated - this is just a first version (with the RDFa file as its starting point).
>> 
>> Thanks,
>> Holger
>> 
>> 
>> 
>> On 5/8/2013 11:43, Kingsley Idehen wrote:
>>> On 5/7/13 9:22 PM, Holger Knublauch wrote:
>>>> On 5/8/2013 10:44, Dan Brickley wrote:
>>>>> 
>>>>> 
>>>>> On Wednesday, May 8, 2013, Holger Knublauch wrote:
>>>>> Looking at the OWL version of schema.org at
>>>>> 
>>>>>     http://schema.org/docs/schemaorg.owl
>>>>> 
>>>>> I notice that this seems to be a rather old version, while the RDFa version
>>>>> 
>>>>>     http://schema.org/docs/schema_org_rdfa.html
>>>>> 
>>>>> seems to be more recent. (When) will the OWL version be fixed?
>>>>> 
>>>>> Is it useful? what do you prefer? The use of OWL is pretty weak since we're so flexible.
>>>> 
>>>> It's not very useful in its current form, yet I believe it can be made very useful with a few changes. You guys are probably wasting an opportunity to get more "semantic web" people on board. My guess is that most OWL people look at both prominent online versions (the official one and the one of rdfs.org) and walk away because they are rather unusable.
>>>> 
>>>> Specifically, I would do the following transformations (and as an exercise I have actually implemented the required SPARQL updates based on the current OWL file):
>>>> 
>>>> - Clean up the owl:unionOfs with one member
>>>> - Convert any usage of schema.org datatypes with xsd ones
>>>> - Convert rdfs:range (Number or String) to xsd:float
>>>> 
>>>> Along with a simple instance data converter, the ontology could be changed to
>>>> - Replace schema:Thing with owl:Thing
>>>> - Replace schema:name with rdfs:label
>>>> - Replace schema:description with rdfs:comment
>>>> - Delete schema:url (as it's basically the URI of the subject)
>>>> 
>>>> Manual clean up should
>>>> - Add cardinality restrictions
>>>> - Declare owl:inverseOf relationships
>>>> - Mark outdated properties (such as the plural forms) as owl:deprecated.
>>>> 
>>>> Could this info be made available anywhere in machine readable form? I am pretty sure not only the RDF/OWL mapping could use this info.
>>>> 
>>>>> 
>>>>> Does rdf/xml vs rdfa (or json-ld etc) matter to you? What about the choice of all in one big file vs per-term?
>>>> 
>>>> It would be good to be able to owl:import something. The RDFa version does some things better than the OWL version, but not everything is perfect: properties with multiple rdfs:domains should use owl:unionOf (I guess RDFa has trouble representing this?).
>>>> 
>>>> And of course why not have the URIs dereferencable as true linked data... This should be a trivial feature to add for an organization that large. Even if just to show that the people behind schema.org do care about the semantic web community.
>>>> 
>>>> I am tempted to create our own copy based on the distilled RDFa version on some topbraid.org address because I believe there is much more potential here.
>>> 
>>> Yes, there is and I encourage you to crack on if you have the time. Basically, make your tweak and then just publish the revised document at URL.
>>> 
>>>> One specific use case is that many of our customers build their own ontologies with concepts that are reinvented all the time - Person, Address etc. While our tooling is generic and can work with any ontology, it would be better to ship our product with some starter ontology and I believe schema.org could become the foundation of this. For this starter ontology, we would define some customized forms and views, e.g. so that addresses show street address above postal code etc. We could also define some out of the box web services with typical queries, reports etc. Clearly there are other product ideas in this space that the schema.org effort could also benefit of. The more alignment of data the better for everyone. Even if RDFa and Microdata will remain the vehicles of distributing schema.org instance data, these web pages may be generated by a triple store.
>>> 
>>> Not may, they will, and have been :-)
>>> 
>>>> 
>>>> Sorry if this is repeating some discussions that have already happened elsewhere... I am trying to catch up.
>>>> 
>>>> HTH
>>>> Holger
>>>> 
>>> 
>>> 
>>> -- 
>>> 
>>> Regards,
>>> 
>>> Kingsley Idehen	      
>>> Founder & CEO 
>>> OpenLink Software     
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>>> 
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>>> 
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>>> 
>>> 
>>> 
>>> 
>>> 
>> 
>> 
>> 
>> 
>> -- 
>> Bernard Vatant
>> Vocabularies & Data Engineering
>> Tel :  + 33 (0)9 71 48 84 59
>> Skype : bernard.vatant
>> Blog : the wheel and the hub
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> 

--------------------------------------------------------
martin hepp
e-business & web science research group
universitaet der bundeswehr muenchen

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Received on Tuesday, 14 May 2013 14:47:27 UTC