Question that I find important in the presence of such merging of models or re-use of the URIs in the different context is what the modeler is trying to accomplish.
rdfs:subClassOf has clear semantics: 1. Both subjects and object are classes 2. Classes describe sets of instances that are class members. By describe, we mean identify properties they may have and property values using formal KR languages such as OWL and SHACL. Another, alternative way to describe a class is by enumerating a complete, finite list of its members. If a modeler is not clear what are the instances of a class she is describing, she should not be declaring it a class. 3. All instances of the subject class are also instances of the object class. 4. Everything said about members of the object class using OWL restrictions or SHACL constraints applies to the members of the subject class. For example, if Mountain is a class and Himalayas a subclass of it and we used a constraint to say that mountains have elevation and it must be numeric, then the same is true for every instance of Himalayas. Skos:broader has no clear semantics other than it connects two concepts. Nothing else is defined and one could use skos:broader to build any hierarchy for any purpose. For example, a real (implied) relationship may be partitive (e.g., Germany is part of European Union or Engine is a part of a Car) or is-a (e.g., Human is a Mammal) or something else or even a mixture of different relationships: Joe Smith’s BMW (in instance of a car) has model BMW 230i (an instance of Car Model class) which is part of BMW 2 Series (an instance of Car Series class) which is manufactured by BMW (an instance of Organization or an instance of a Brand, depending on what you are modeling and for what reasons). In a SKOS Taxonomy, we may commonly see BMW 230i skos:broader BMW 2 Series skos:broader BMW. I can't think of reasons for wanting to connect two classes that are already connected by rdfs:subClassOf relationship with skos:broader relationship. The underlying question is really about whether the same resource should/could be both, an OWL Class and an instance of skos:Concept. Saying that the same resource is a class and an instance is called punning. Restrictions on punning have been relaxed in OWL-2 because new algorithms were designed that would ensure that DL processing did not get into a tizzy when punning is done a certain way. This is quite academic anyhow since there are very few DL reasoners in the world and no one uses them outside of academia. Personally, I believe that situations where punning may make sense are extremely rare. Human language is imprecise and it is common for us to use the same word when we mean different things. As people, we understand what is meant through the context of conversation. We know when a person is talking about BMW 230i as a set of all cars that have this model or when they talk about it as an instance of a car model. These are two different things in the world and they have different properties. Computers can’t make the contextual distinction if we use the same URI for two different things. Modelers should be precise in the meaning of a resource they are identifying and describing if their models are intended for machine processing. > On Oct 8, 2019, at 11:31 AM, 'Bohms, H.M. (Michel)' via TopBraid Suite Users > <[email protected]> wrote: > > > In: > https://www.w3.org/2006/07/SWD/SKOS/skos-and-owl/master.html > <https://www.w3.org/2006/07/SWD/SKOS/skos-and-owl/master.html> > > its is said: > “ > To illustrate these patterns, let's start with the following semi-formal > conceptualisation: > ex:mountains rdf:type skos:Concept; > skos:prefLabel "Mountains"@en. > > ex:himalayas rdf:type skos:Concept; > skos:prefLabel "Himalayas"@en; > skos:broader ex:mountains. > > ex:everest rdf:type skos:Concept; > skos:prefLabel "Everest"@en; > skos:broader ex:himalayas. > Overlay SKOS with OWL > In this pattern, we use OWL to overlay additional semantics on the same > vocabulary, e.g. by adding the following triples: > ex:mountains rdf:type owl:Class. > > ex:himalayas rdf:type owl:Class; > rdfs:subClassOf ex:mountains. > > ex:everest rdf:type ex:himalayas. > If the two sets of triples are merged, then this pattern necessarily leads to > an OWL Full representation, because an instance of skos:Concept might also be > an instance of owl:Class. > > “ > > Is the red statement really true? And if yes, is it really an issue here? > > (maybe it was under owl1 but under owl2 not different?) > > thx for advice, Michel > > > > > Dr. ir. H.M. (Michel) Böhms > Senior Data Scientist > > T +31888663107 > M +31630381220 > E [email protected] <mailto:[email protected]> > Location > <https://www.google.com/maps/place/TNO+-+Locatie+Delft+-+Stieltjesweg/@52.000788,4.3745183,17z/data=!3m1!4b1!4m5!3m4!1s0x47c5b58c52869997:0x56681566be3b8c88!8m2!3d52.000788!4d4.376707> > > > <image001.gif> <http://www.tno.nl/> > This message may contain information that is not intended for you. If you are > not the addressee or if this message was sent to you by mistake, you are > requested to inform the sender and delete the message. 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