Re: rdfs:class versus owl:class in SOSA-Core

>
> I was not at the meeting, so I may have missed something, but what is 
> the rationale for forbidding certain constructs?  If there is an 
> owl:inverseOf in the ontology, the RDFS reasoners won't care. Nobody 
> who's not using/interested in owl:inverseOf will care.
>
> However, in the case of owl:inverseOf, I don't think it is a question 
> of whether we want to use the construct or not. It is a question of 
> deciding whether we allow ourselves to define both a property and its 
> inverse. If we have properties like ex:hasChild and ex:hasParent, it 
> would be silly not to make explicit the inverse relationship. If the 
> decision is about not having both a property and its inverse, then the 
> need to use or not owl:inverseOf is only an inevitable consequence of 
> the other decision. 

Exactly what I (and others said), see the other emails and discussions. 
Using owl:inverseOf will not hurt any RDFS reasoners and the entire 
point is about what we want to model and not what language to use.

>
> I don't see a reason not to. Not having owl:Class declaration has 
> noticeable consequences. For instance, it always troubles me that 
> Protégé cannot display the Dublin Core properties and classes. It also 
> troubles me that the DC terms cannot be imported with standard 
> owl:imports, because of the lack of owl class, owl properties 
> declarations. 

+1.

> -rdfs:domain and rdfs:range
>
> Please use these whenever relevant. [...]. You can't go wrong with them. 

This is the only part of your email where I would strongly disagree 
(well, depending on what you mean by 'whenever relevant' :-)) for the 
reasons we discussed here before and that others made when developing 
other ontologies. This is not to say that using them is 'wrong' in some 
sense but that they have to be handled with great care.

Best,
Krzysztof



On 11/09/2016 01:15 PM, Antoine Zimmermann wrote:
> On 09/11/2016 00:20, Armin Haller wrote:
>> Hi Krzysztof,
>>
>> Thanks for your detailed explanations below!
>>
>> Just to clarify, the intention in the meeting to go through a list of
>> what constructs should be in SOSA (as thankfully proposed by Josh) was
>> to be incremental. I was planning to incrementally go through the list
>> of constructs that are either already in our current SOSA proposal or
>> could be imagined to be in it and vote on them. Some, of course have
>> implications, if we decide on owl:inverseOf in our next meeting, we will
>> not be in RDFS entailment.
>
> I was not at the meeting, so I may have missed something, but what is 
> the rationale for forbidding certain constructs?  If there is an 
> owl:inverseOf in the ontology, the RDFS reasoners won't care. Nobody 
> who's not using/interested in owl:inverseOf will care.
>
> However, in the case of owl:inverseOf, I don't think it is a question 
> of whether we want to use the construct or not. It is a question of 
> deciding whether we allow ourselves to define both a property and its 
> inverse. If we have properties like ex:hasChild and ex:hasParent, it 
> would be silly not to make explicit the inverse relationship. If the 
> decision is about not having both a property and its inverse, then the 
> need to use or not owl:inverseOf is only an inevitable consequence of 
> the other decision.
>
>
>> If we are already in OWL, then of course it would make sense to use
>> owl:Class, although we do not have to. Therefore, again a vote on
>> owl:Class thereafter.
>
> I don't see a reason not to. Not having owl:Class declaration has 
> noticeable consequences. For instance, it always troubles me that 
> Protégé cannot display the Dublin Core properties and classes. It also 
> troubles me that the DC terms cannot be imported with standard 
> owl:imports, because of the lack of owl class, owl properties 
> declarations.
>
>
>> I can think of the following list to vote on in our next meeting,
>> incrementally. And we stopped at owl:inverseOf this meeting I just saw
>> in the minutes.
>>
>> -rdfs:class
>
> see above and related emails.
>>
>> -owl:inverseOf
>
> see above.
>>
>> -owl:AnnotationProperty
>>
>> -           owl:ObjectProperty
>
> owl:AnnotationProperty, owl:ObjectProperty and owl:DatatypeProperty, 
> like owl:Class, do not add expressiveness to the language. However, 
> they help OWL tools figuring out what the terms are.
>
> FWIW, in OWL 2 RDF-based semantics, owl:ObjectProperty is equivalent 
> to rdf:Property. owl:AnnotationProperty and owl:DatatypeProperty are 
> both subClassOf rdf:Property.
>
>>
>> -owl:Class
>
> see above.
>
>>
>> -rdfs:domain and rdfs:range
>
> Please use these whenever relevant. When used with an atomic class, 
> they are fully supported by RDFS, OWL 2 EL, OWL 2 QL, OWL 2 RL, OWL 2 
> DL, OWL 2 Full, ter Horst semantics, RDFS++. You can't go wrong with 
> them.
>
>>
>> -rdfs:subClassOf
>
> Come on! Do we need to vote on this one?
>
>>
>> -           owl:Restriction
>
> There are many forms of restrictions, each one should be considered 
> individually. I don't see much reason to forbid ourselves to use any 
> of them because anyone can just ignore those they don't like. However, 
> they should be used sensibly because we should not prevent use cases 
> that we have not foreseen. I'd prefer an ontology that has very little 
> restrictions with precise documentation to prevent misusing the terms, 
> rather than an overly restrictive one. Look at schema.org: painfully 
> non-restrictive, delightfully useful.
>
>
> --AZ
>
>>
>> Please do think about these and if you think they should or should not
>> be in the core or if there is anything else we desperately would need.
>>
>> Kind regards,
>> Armin
>>
>> *From: *Krzysztof Janowicz <jano@geog.ucsb.edu>
>> *Date: *Wednesday, 9 November 2016 at 10:01 am
>> *To: *Joshua Lieberman <jlieberman@tumblingwalls.com>, Simon Cox
>> <Simon.Cox@csiro.au>, Kerry Taylor <kerry.taylor@anu.edu.au>, Armin
>> Haller <armin.haller@anu.edu.au>
>> *Cc: *SDW WG Public List <public-sdw-wg@w3.org>
>> *Subject: *rdfs:class versus owl:class in SOSA-Core
>>
>> Hi,
>>
>> Sorry for being so picky about this during our meeting but I do not want
>> us to take decisions that have consequences that we can not yet foresee.
>>
>> To the best of my knowledge (and please correct me if I am wrong):
>>
>> Under the semantics of OWL1, rdfs:class and owl:class are only
>> equivalent for OWL-Full. For OWL-DL (and OWL-Lite) owl:class is a
>> subclass of rdfs:class.
>>
>> This means that every valid document in OWL will be a valid document in
>> RDFS, however *not* every rdfs:class is an owl:class. I do not want us
>> to end up in OWL-Full because of this.
>>
>> For OWL2, I found this: 'owl:Class rdfs:subClassOf rdfs:Class . "
>> (https://www.w3.org/TR/owl2-rdf-based-semantics/). Things may be more
>> complicated here due to OWL2 punning and they may well turn out to be
>> equivalent, I will check this later.
>>
>> If we decide to restrict ourself to only using RDFS for SOSA-core, and I
>> am not in favor of this, then we may have to go with rdfs:class.
>> However, we have not yet taken this decision and have also not discussed
>> which axioms and language to use for SSN. As Sosa-core and SSN will be
>> aligned, this may have more consequences that we should consider. It
>> also seems like many of us are in favor of using inverseOf, so we would
>> be using OWL (and its formal semantics) anyway. Note that this does not
>> do any harm to an RDFS-only tool/user as for those the inverseOf axiom
>> will simply have no formal semantics. Still all other triples that use
>> both relations will still be just fine.
>>
>> Given the subclasssing, I do not see any problems using owl:class, but
>> we may accidentally end up in OWL-full or with being incompatible to the
>> standards if we opt for rdfs:class. Again, I am happy to be corrected.
>> At least, I do not see harm in simply using owl:class.
>>
>> Finally, and from very pragmatic point of view: ontologies that are
>> under very heavy use such as the DBpedia ontology simply use owl:class
>> and I have not yet seen any issues or complaints about that. See, for
>> example, http://dbpedia.org/ontology/City "dbo:City    rdf:type
>> owl:Class ." The same is true for the goodrelations ontology and so
>> forth (but I admit that this is due to the more complex axiomatization
>> they use).
>>
>> I hope this will start a productive discussion.
>>
>> Thanks for reading,
>>
>> Krzysztof
>>
>


-- 
Krzysztof Janowicz

Geography Department, University of California, Santa Barbara
4830 Ellison Hall, Santa Barbara, CA 93106-4060

Email: jano@geog.ucsb.edu
Webpage: http://geog.ucsb.edu/~jano/
Semantic Web Journal: http://www.semantic-web-journal.net

Received on Wednesday, 9 November 2016 22:47:01 UTC