Re: doubt about "Synset / Concept" class

Uhm, you're talking of two different things here.
Indeed SKOS in RDF-OWL has a semantics (intensional and extensional), but this is true also for WordNet synsets, senses and words, as well as for any other datum encoded in RDF-OWL. For that reason should we then use only ontolex:reference for everything?
And I also see that subtle distinctions can be hard to digest to non-experts. But no distinctions at all is an even worse problem. With the design rationale that any OWL individual can be used as a reference *in general* (in particular cases is of course perfectly fine to treat them all as references), nothing can justify why SKOS concepts are ok and others not.
I see two escapes:

1) we maintain the suggestion to use skos:exactMatch for mapping to SKOS, explaining why and how, as it's common in design patterns for software, ontologies, and data (people like being explained useful things sometimes ;))
2) we collapse the properties, but we create an OWL axiom that states e.g. the following general class axiom: 
 (ontolex:reference some skos:Concept) owl:equivalentTo (skos:exactMatch some skos:Concept)

Aldo

On May 8, 2013, at 4:52:54 PM , Philipp Cimiano <cimiano@cit-ec.uni-bielefeld.de> wrote:

> John,
> 
> of course skos:Concepts have a formal interpretation and thus an extension much as owl:Classes.
> 
> So I am not assuming:
> 
> :cat rdf:type skos:Concept ⊨ :cat rdf:type owl:Thing
> 
> But a SKOS document is an RDF document and thus has an RDF Interpretation which also assign denotations to the URIs in the document.
> 
> Further, of course SKOS documents has a semantics, which is defined in OWL.
> 
> For example skos:transitiverBroader is defined as a OWL transitive property.
> 
> And btw. skos:Concept is defined as being an owl:Class, i.e. skos:Concept rdf:type owl:Class (see axiom S1 in http://www.w3.org/TR/2009/REC-skos-reference-20090818/)
> 
> So SKOS is as axiomatized as any other OWL ontology ;-)
> 
> So we should not treat SKOS concept as being really different from OWL concepts at the lexicon level. Such distinctions are very subtle and people will not grasp this difference, having doubts on which property to use in a particular case. This will compromise the usability of the model IMHO
> 
> Philipp.
> 
> Am 08.05.13 21:36, schrieb John McCrae:
>> 
>> 
>> 
>> On Wed, May 8, 2013 at 5:56 PM, Philipp Cimiano <cimiano@cit-ec.uni-bielefeld.de> wrote:
>> Dear all,
>> 
>>     I am not with Aldo and John here.
>> 
>> I think introducing two different properties makes our model unnecessarily complex. 
>> 
>> Neither model introduces any new properties, the first allows reference to have two domains (skos:Concept and owl:Thing) but means only one (skos:Concept). The second model uses skos:exactMatch for matching within a SKOS model and differentiates reference  and means by domain (owl:Thing and skos:Concept respectively).
>>  
>> We said we use "reference" when the meaning is expressed by an extensional entity where we defined extensional as "having an extension in some model of the theory". I agreed to that.
>> 
>> According to this, a particular skos:Concept (an individual) has as much as an extensional interpretation as a particular owl:Class, or an owl:Individual to stay at the same level.
>> Eh? You are saying: "SKOS concepts have an extension in some model of the theory". This seems very odd, SKOS does not have any formal semantics, therefore how can it have models and extensions? The reasoning seems circular, if I assume SKOS concepts have extensions like an OWL entity then SKOS concepts are like OWL entities because they have extensions.
>> 
>> Of course, a particular skos:Concept is an individual from an RDF/OWL perspective and is also interpreted as some individual in the corresponding domain, much like an owl:Individual. So a model assigns some extensional interpretation to both skos:Concepts and owl:Individuals. Where is then the essential difference that prevents us using the same property for both then?
>> Again, you are assuming that as 
>> 
>> :cat rdf:type skos:Concept ⊨ :cat rdf:type owl:Thing
>> 
>> Ergo, :cat has an extension in OWL. But this only true because you applied an OWL reasoner, and more importantly the meaning has changed: the OWL reasoner has               only indicated that there are is a (individual) thing (the genus of cats), where as the SKOS concept intended an extension as the class of cats. 
>>  
>> 
>> Surely, skos:Concept are per definition "intensions", but technically they are extensional entities according to our definition, i.e. owl:Individual or rdf:Thing.
>> 
>> Further, it is perfectly fine for a skos:Concept to be an owl:Class (see http://www.w3.org/TR/2009/REC-skos-reference-20090818/)
>> 
>> True, but more importantly a skos:Concept can also be an owl:DatatypeProperty, an owl:ObjectProperty and an owl:Thing. The difference is the underspecification.
>> 
>> 
>> What do we use then? "reference" or "means"? ;-)
>> 
>> 
>> Treating skos:Concept and owl:Class as different types of meaning seems too subtle for people who want to use the model in practice as they will always wonder which is the right property to use.
>> 
>> Regards,
>> John 
>> 
>> 
>> Philipp.
>> 
>> Am 08.05.13 13:08, schrieb John McCrae:
>>> Hi Aldo,
>>> 
>>> Names in the previous example are not fixed of course. I also don't like "means" that much I just haven't got a better alternative yet. (synset is too WordNet-specific,                           means/meaning/concept are too broad)
>>> 
>>> Regards,
>>> John
>>> 
>>> 
>>> On Wed, May 8, 2013 at 1:02 PM, Aldo Gangemi <aldo.gangemi@cnr.it> wrote:
>>> Hi, I agree with John, we really seem on the same wave now :), in fact I agree with Model 2 being far better.
>>> Only, should we really use ontolex:means to link senses and synsets? It's a bit too broad as a name for a specific relation like that, isn't it?
>>> 
>>> Aldo
>>> 
>>> On May 8, 2013, at 6:37:22 AM , John McCrae <jmccrae@cit-ec.uni-bielefeld.de> wrote:
>>> 
>>>> Hi Jorge, all,
>>>> 
>>>> Thanks for your comment, I agree this is an issue we should discuss. I think that it is clearly wrong to continue to treat skos:Concepts as ontological elements, they aren't and we shouldn't really confuse them. The question of whether we should still use SKOS terminologies as systems of reference for the model also seems clear to me (of course we should). 
>>>> 
>>>> The question then boils down to this essential question: do we use the same property to reference both a skos:Concept and an ontology entity? 
>>>> 
>>>> This leads to two variation on the model:
>>>> 
>>>> Model 1. (Same property)
>>>> 
>>>> With synsets
>>>> 
>>>> :corn --ontolex:sense-> :corn_sense1 --ontolex:means-> wordnet:corn_n_xxx --ontolex:conceptualizes-> fao:Corn (a skos:Concept)
>>>> :corn --ontolex:sense-> :corn_sense1 --ontolex:means-> wordnet:corn_n_xxx --ontolex:conceptualizes-> dbpedia:Corn (a owl:Class)
>>>> 
>>>> Without synsets
>>>> 
>>>> :corn --ontolex:sense-> :corn_sense1 --ontolex:reference-> fao:Corn (a skos:Concept)
>>>> :corn --ontolex:sense-> :corn_sense1 --ontolex:reference-> dbpedia:Corn (a owl:Class)
>>>> 
>>>> Model 2. (Different property)
>>>> 
>>>> With synsets
>>>> 
>>>> :corn --ontolex:sense-> :corn_sense1 --ontolex:means-> wordnet:corn_n_xxx --skos:exactMatch-> fao:Corn (a skos:Concept)
>>>> :corn --ontolex:sense-> :corn_sense1 --ontolex:means-> wordnet:corn_n_xxx --ontolex:conceptualizes-> dbpedia:Corn (a owl:Class)
>>>> 
>>>> Without synsets
>>>> 
>>>> :corn --ontolex:sense-> :corn_sense1 --ontolex:means-> fao:Corn (a skos:Concept)
>>>> :corn --ontolex:sense-> :corn_sense1 --ontolex:reference-> dbpedia:Corn (a owl:Class)
>>>> 
>>>> With further linking valid of
>>>> 
>>>> fao:Corn --ontolex:conceptualizes-> dbpedia:Corn
>>>> 
>>>> 
>>>> I prefer model two as it makes a clearer distinction between terminologies and ontologies, doesn't require linking two SKOS concepts with an ontolex property (which we should avoid as it is not our job to fix SKOS) and allows us to define a natural property for linking terminologies to ontologies.
>>>> 
>>>> Regards,
>>>> John
>>>> 
>>>> 
>>>> 
>>>> On Fri, May 3, 2013 at 2:58 PM, Jorge Gracia <jgracia@fi.upm.es> wrote:
>>>> Dear Philipp, all
>>>> 
>>>> I am not able to join the telco today, sorry. But let me to formulate
>>>> a quick question about John's model
>>>> http://www.w3.org/community/ontolex/wiki/File:John-modelling.png);
>>>> maybe you can treat it today.
>>>> Following the previous discussions I can understand the inclusion of
>>>> the new class "Synset / Concept". My doubt is: despite the fact that
>>>> skos concepts could be represented with this new class, can we
>>>> alternatively continuing treating skos concepts (of external skos
>>>> ontologies) as "ontology entities"? (as in the IFLA example presented
>>>> last week). For me this option is very natural, fully compliant with
>>>> R3 "semantics by reference" and we shouldn't lose it.
>>>> 
>>>> Best regards,
>>>> Jorge
>>>> 
>>>> 
>>>> 2013/5/2 Philipp Cimiano <cimiano@cit-ec.uni-bielefeld.de>:
>>>> > Dear all,
>>>> >
>>>> >  this is a gentle reminder that we will have our regular ontolex telco
>>>> > tomorrow.
>>>> >
>>>> > I intend to discuss the model proposed by John on the basis of the
>>>> > contributions of all of you.
>>>> > I would like to see if there is a chance that we agree on this model as a
>>>> > building block for the further work.
>>>> >
>>>> > Here is a link to the conference metadata including access details:
>>>> >
>>>> > http://www.w3.org/community/ontolex/wiki/Teleconference,_2013.03.05,_15-16_pm_CET
>>>> >
>>>> > Best regards,
>>>> >
>>>> > Philipp.
>>>> >
>>>> > --
>>>> > Prof. Dr. Philipp Cimiano
>>>> > Semantic Computing Group
>>>> > Excellence Cluster - Cognitive Interaction Technology (CITEC)
>>>> > University of Bielefeld
>>>> >
>>>> > Phone: +49 521 106 12249
>>>> > Fax: +49 521 106 12412
>>>> > Mail: cimiano@cit-ec.uni-bielefeld.de
>>>> >
>>>> > Room H-127
>>>> > Morgenbreede 39
>>>> > 33615 Bielefeld
>>>> >
>>>> >
>>>> 
>>>> 
>>>> 
>>>> --
>>>> Jorge Gracia, PhD
>>>> Ontology Engineering Group
>>>> Artificial Intelligence Department
>>>> Universidad Politécnica de Madrid
>>>> http://delicias.dia.fi.upm.es/~jgracia/
>>>> 
>>>> 
>>> 
>>> 
>> 
>> 
>> -- 
>> Prof. Dr. Philipp Cimiano
>> Semantic Computing Group
>> Excellence Cluster - Cognitive Interaction Technology (CITEC)
>> University of Bielefeld
>> 
>> Phone: +49 521 106 12249
>> Fax: +49 521 106 12412
>> Mail: cimiano@cit-ec.uni-bielefeld.de
>> 
>> Room H-127
>> Morgenbreede 39
>> 33615 Bielefeld
>> 
> 
> 
> -- 
> Prof. Dr. Philipp Cimiano
> Semantic Computing Group
> Excellence Cluster - Cognitive Interaction Technology (CITEC)
> University of Bielefeld
> 
> Phone: +49 521 106 12249
> Fax: +49 521 106 12412
> Mail: cimiano@cit-ec.uni-bielefeld.de
> 
> Room H-127
> Morgenbreede 39
> 33615 Bielefeld