Re: Dark triples, current closure / entailment rules, can someone clarify?

On 2002-06-25 17:12, "ext Jan Grant" <Jan.Grant@bristol.ac.uk> wrote:

> 
> On Tue, 25 Jun 2002, Jan Grant wrote:
> 
>> 
>> On Mon, 24 Jun 2002, patrick hayes wrote:
>> 
>>> 
>>>> Pat indicated at the F2F that entailments "accidentally" drawn would be
>>>> "harmless".
>>> 
>>> RDF entailments, yes.
>>> 
>>>> Can someone clear up this example for me?
>>>> 
>>>> A:
>>>> <eg:foo1> <rdf:subPropertyOf> <dark:eg:foo2> .
>>>> <dark:eg:foo2> <rdf:subProperotyOf> <eg:foo3> .
>>>> 
>>>> <eg:a> <eg:foo1> <eg:b> .
>>>> 
>>>> B:
>>>> <eg:foo1> <rdf:subPropertyOf> <dark:eg:foo2> .
>>>> <dark:eg:foo2> <rdf:subProperotyOf> <eg:foo3> .
>>>> 
>>>> <eg:a> <dark:eg:foo2> <eg:b> .
>>>> 
>>>> C:
>>>> <eg:foo1> <rdf:subPropertyOf> <dark:eg:foo2> .
>>>> <dark:eg:foo2> <rdf:subProperotyOf> <eg:foo3> .
>>>> 
>>>> <eg:a> <eg:foo3> <eg:b> .
>>>> 
>>>> 
>>>> Does A |= C? Does A |= B? B |= C?
>>> 
>>> Yes:
>>> A|= C (by subproperty chaining and then the subproperty closure rule)
>>> No:
>>> A |= B (dark conclusion)
>> 
>> Actually, for the same reason, isn't this a "yes"? Because the non-dark
>> statements are a strict subset of the antecedent?
> 
> OK, thinking more about this: this is a technicality. However, closure
> rules for URL-prefix-based darkening would all have to be rewritten to
> not add triples if the predicate would cause darkening. With a simple
> bit flag then the closure rules don't need rewriting because one can
> simply state, "the closure rules are applied only o non-dark triples and
> only produce non-dark triples".
> 
> s/non-dark/asserted/g if appropriate.

And likewise, if reification were used to express those unasserted
triples, then closure rules would not need any rewriting at all,
since they already (presumably) ignore unasserted statements.

Patrick

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