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On Fri, Nov 07, 2014 at 08:08:26AM -0500, [log in to unmask] wrote:
> > Once a class is declared to have an rdfs:subClassOf relation to
> > another class, that declaration becomes part of the formal semantics
> > of the class.  Once a property is related to a class through
> > rdfs:domain and rdfs:range, that declaration becomes part of the
> > formal semantics of the property.
> 
> It's not clear to me what you mean by "the formal semantics". There is
> not a single formal semantics for a set of triples. There are the
> various semantics under RDF, RDFS, OWL, etc., which are compatible by
> design, but are _certainly distinct_.

As in [1], let
    
1)  P rdfs:domain C

This entails:

2)  C rdf:type rdfs:Class

One may choose not to _apply_ RDFS inferencing in order to materialize
triple 2 in a given dataset, but that does not change the fact that this
is what "P rdfs:domain C" actually entails.  I am not aware of any
RDF-family semantics by which triple 2 would not be inferred.

[1] http://www.w3.org/TR/rdf-schema/#ch_domain

> > Whether membership of an instance in a domain or range class is
> > _asserted_ in a given dataset, or _inferred_, is purely a practical
> > question having to do with things like "expense," "response time",
> > or as Simeon points out, whether it "make[s] the data easy and
> > efficient to use" or provides "clarity of intent" to someone trying
> > to grok the Turtle data. 
> 
> To label something "purely a practical question" is very far from
> dismissing it, if we expect to do anything with Linked Data other than
> talk about it.

By saying it is a practical question, I am not dismissing it in the
least!  I emphatically agree that the practicalities are very important
if we expect to do anything with Linked Data other than talk about it.
And if you say, for example, that this-or-that _must_ be asserted in the
data, and not just left to be inferred, then there must be a way to say
that.  The BIBFRAME stack _does_ provide a way to say that; it's just
that that way is orthogonal to the RDF semantics.

> >  Simply leaving a formal-semantic relationship unasserted, to be
> >  clear, has no affect on formal semantics.  
> 
> I'm afraid I don't understand this statement. What do you mean by a
> "formal-semantic relationship"?

In

    P rdfs:domain C

the subject P is related object C via the property rdfs:domain, and that
relationship is subject to semantics that are "formally" defined ("This 
document... provides an exact formal specification" [2]).

[2] http://www.w3.org/TR/rdf11-mt/

> > I do not understand the point of coining lots of new classes for the
> > BIBFRAME vocabulary.  An RDF vocabulary cannot itself provide ways
> > to prevent "multiple, incompatible ways" of using the vocabulary,
> > which I take to be Rob's objective.  If data consistency, clarity of
> > intent (for humans), and efficiency of processing are indeed the
> > objectives, I do not understand why the discussion here is about
> > trying to do this in BIBFRAME's RDF vocabulary, which does not
> > provide the language for exerting such control.
> 
> This is not at all, to my understanding, a matter of control. 
> [...] The idea is not at all, to my understanding, to "to prevent 'multiple,
> incompatible ways' of using the vocabulary", 

I misunderstood!

> It is a matter of providing a flexible and easy-to-use means of
> extension.  [...] it is to provide a straightforward and simple way of
> extending the vocabulary. That is a far more powerful and lasting
> effect.

I'm not following... Coining lots of new classes provides a simple
way of extending the vocabulary?  I can see that coining new classes
does indeed extend the vocabulary, but I'm missing the point...

Tom

-- 
Tom Baker <[log in to unmask]>