Re: Missing subClassOf?

On 28 August 2013 16:32, Alex Milowski <alex@milowski.com> wrote:

> Yet, for example, the definition of http://schema.org/domainIncludes says
> the expected value is schema:Class when in the RDFa/RDFS schema use it is
> an instance of rdfs:Class.
>

Any schema:Class will also be an rdfs:Class and an owl:Class (regardless of
whether that is directly and explicitly asserted).


> It doesn't make a lot of sense to define domainIncludes/rangeIncludes if
> they're only to be used within the context of RDFa where the respective
> values are not as they say.  Yet, if they are to be used within Microdata,
> then you need subClassOf.
>
> This just points out the sad state of "schema" or "constraint" languages
> for these kinds of things.  If schema.org needs to define
> domainIncludes/rangeIncludes (which it does), shouldn't they be defined
> just within the context of the schema syntax and not for the type hierarchy
> described by that syntax?
>

They're a syntax-neutral utility vocabulary that sits alongside the basic
RDFS machiner (i.e. they not bound to microdata or json-ld or rdfa or
rdf/xml or whatever). This is an idea entirely anticipated in
http://www.w3.org/TR/rdf-schema/   ---

"This specification does not attempt to enumerate all the possible forms of
vocabulary description that are useful for representing the meaning of RDF
classes and properties. Instead, the RDF vocabulary description strategy is
to acknowledge that there are many techniques through which the meaning of
classes and properties can be described. Richer vocabulary or 'ontology'
languages such as DAML+OIL, W3C's
[OWL<http://www.w3.org/TR/rdf-schema/#ref-owl>]
language, inference rule languages and other formalisms (for example
temporal logics) will each contribute to our ability to capture meaningful
generalizations about data in the Web. RDF vocabulary designers can create
and deploy Semantic Web applications using the RDF vocabulary description
language 1.0 facilities, while exploring richer vocabulary description
languages that share this general approach."

The reason to give a schema.org definition of 'Class' and 'Property' is for
self-contained documentation. The reason to express that it is basically
the same notion as rdfs:Class, rdf:Property and owl:Class is to support
wider interoperability.

The properties domainIncludes and rangeIncludes are not just for RDFa use,
but they're primarily there for schema.org to capture / express  / share
the fairly loose meaning of its main property<->class associations, without
over-stretching rdfs:range or needing complex OWL expressions.

Dan