Re: N3 and TriG [was: Hello, n3]

HI Dörthe,

> In case of TriG this really depends on the interpretation you choose. But given, that you choose some kind of open interpretation, would that be different from saying in N3 something like:
> 
> :graph :includesTriples {:a :b :c. :d :e :f}.

That could be the same thing, but my point is rather that
    {:a :b :c. :d :e :f}
means something different in TriG and N3, despite the same syntax.
(Where “means” also captures the fact that this meaning in TriG is open,
 whereas in N3 it is clear.)

> Interesting that you say that "the equal sign" got dropped. Reading this I would have expected that you understand a graph as closed.

Well, not my words but Chris’s and Richard’s:

>> optional = graph naming operator and optional "." after each graph for N3 compatibility.

>> the optional = operator and an optional "." after each Named Graph
>> are used in order to make TriG documents compatible with the N3 syntax.

—http://wifo5-03.informatik.uni-mannheim.de/bizer/trig/


If they intended “compatibility” as purely syntactical compatibility, then they’re right;
if it was intended as semantic compatibility, something’s off.

> Remember that there is no "interpretation" of TriG. I think you refer to this sentence:
> 
> "BlankNodes sharing the same label in differently labeled graph statements are considered to be the same BlankNode.”

Indeed; so this seems to imply that all bank nodes with the same label
(in the same document??) bear the same interpretation—whatever that interpretation is.
Or could the same blank node have different interpretations depending on context,
i.e., is interpretation a function of the entity and the graph it resides in?

> regardless of how we formalise it, the fact that a blank node in RDF and thereby also in N3 is a variable with an implicit quantifier which also has a position (inside or outside the quote?) makes this a concept we need to be very careful with. So, I would also careful with ad-hoc alignments and carefully see which use cases we exclude with our formalisations.

Definitely, we need to think this through.

In that context, http://aidanhogan.com/docs/certain_answers_sparql_blank_nodes.pdf is interesting
as it is an exploration of what would happen if blank nodes in RDF datasets indeed were used as existentials.

Best,

Ruben

Received on Wednesday, 12 December 2018 11:04:40 UTC