On Nov 24, 2013, at 12:08 PM, Michael Brunnbauer <brunni@xxxxxxxxxxxx> wrote: (01)
>
> Hello Pat,
>
> On Sun, Nov 24, 2013 at 11:03:25AM -0600, Pat Hayes wrote:
>> It is hard to know how to make prominent warnings about what is NOT
>entailed, as so much is not entailed. Let me ask you, why did you assume that
>it was entailed?
>
> I saw that a (strict) RDFS reasoner using multiple passes would produce the
> ABox consequences of those additional TBox entailments. As my reasoner does
>not
> use multiple passes, but tries to produce all entailments of a new TBox/ABox
> fact in one step, I had to include those additional entailments into my
> internal TBox. (02)
OK, I see. (03)
> As this TBox stays internal, there should be no problem. But I think I was not
> aware that producing the TBox entailments as new facts would not be covered
>by
> RDFS. (04)
Right. One might sum up the 'official' (minimal, intensional) semantics of RDFS
as being that which allows inferences from Tbox to Abox but not from Tbox to
Tbox, except using reflexive/transitivity (which are put in as explicit
semantic axioms.) In general, RDFS does not endorse inference patterns which
rely on the intuition "all instances of this class must be in X, therefore the
class is a subclass of X". Which is, of course, an extensional intuition which
thinks of classes as sets. So while the semantics ensures that (05)
p subProperty q
q domain D
x p b (06)
together entail (07)
x type D (08)
for any x, it still does not enforce (09)
p domain D (010)
This allows for cases where domains are attached to properties for other
reasons than only obtaining the canonical RDFS domain entailment (011)
x p b & p domain D |= x type D (012)
However, if indeed that is your only reason for making a domain assertion, then
the 'missing' axiom could be assumed harmlessly by your reasoning engine. And
similarly for rdfs:range, of course. (013)
Pat (014)
>
> Regards,
>
> Michael Brunnbauer
>
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