On Sep 20, 2013, at 10:54 AM, Jeremy J Carroll wrote:
>
>
> On Sep 20, 2013, at 2:45 AM, Pat Hayes <pha...@ihmc.us> wrote:
>
>> In the original paper that Jeremy and I (and Chris Bizer) co-wrote, we
>> defined a named graph to be a <name, graph> pair, so the statement
>>
>> GRAPH x:g1 { :a :b :c .}
>>
>> would mean that the IRI x:g1 denotes the pair < x:g1, { :a :b :c .} >. But
>> if someone were to object that this is artificial and unintuitive, I would
>> not defend it overly strongly.
>
> Patrick Stickler was our fourth author.
Of course, sorry. (How can I have forgotten Patrick??)
>
> This actually works; I had forgotten. But it gives all the rights answers to
> all the test cases.
>
> This suggests a different fix that achieves my personal goals and would
> satisfy *my* objections
>
> Ah, I just reread:
>
> [[
> An RDF dataset (see [RDF11-CONCEPTS]) is a finite set of RDF graphs each
> paired with an IRI or blank node called the graph name, plus a default graph,
> without a name. Graphs in a single dataset may share blank nodes. The
> association of graph name IRIs with graphs is used by SPARQL
> [RDF-SPARQL-QUERY] to allow queries to be directed against particular graphs.
>
> Graph names in a dataset may refer to something other than the graph they are
> paired with. This allows IRI referring to other kinds of entities, such as
> persons, to be used in a dataset to identifygraphs of information relevant to
> the entity denoted by the graph name IRI.
>
> When a graph name is used inside RDF triples in a dataset it may or may not
> refer to the graph it names. The semantics does not require, nor should RDF
> engines presume, without some external reason to do so, that graph names used
> in RDF triples refer to the graph they name.
>
> RDF datasets may be used to express RDF content. When used in this way, a
> dataset should be understood to have at least the same content as its default
> graph. Note however that replacing the default graph of a dataset by a
> logically equivalent graph will not in general produce a structurally similar
> dataset, since it may for example disrupt co-occurrences of blank nodes
> between the default graph and other graphs in the dataset, which may be
> important for reasons other than the semantics of the graphs in the dataset.
>
> Other semantic extensions and entailment regimes may place further semantic
> conditions and restrictions on RDF datasets, just as with RDF graphs. One
> such extension, for example, could set up a modal-like interpretation
> structure so that entailment between datasets would require RDF graph
> entailments between the graphs with the same name (adding in empty graphs as
> required).
>
> ]]
>
> hmm, I think I need to update my comment to indicate that on its resolution
> that paragraph should probably change.
>
> Here is a different version.
>
> [[
> An RDF dataset (see [RDF11-CONCEPTS]) is a finite set of RDF graphs each
> paired with an IRI or blank node called the graph name, plus a default graph,
> without a name. Graphs in a single dataset may share blank nodes. The
> association of graph name IRIs with graphs is used by SPARQL
> [RDF-SPARQL-QUERY] to allow queries to be directed against particular graphs.
>
> An RDF interpretation I conforms with the naming of a dataset, if for each
> graph name gn, I(g) is the pair < gn, G > where G is the graph associated
> with gn by the dataset.
>
> An RDF interpretation I of a graph within a dataset SHOULD conform with the
> naming of the dataset.
>
> While graph names in a dataset may **lower case deliberate** refer to some
> other kind of entity, such as persons, this may cause confusion and is not
> RECOMMENDED.
I don't think this will be allowed by the WG, but we could put it to a vote. If
it is accepted, we ought to also put some wording into Concepts to make this
clear.
> RDF datasets may be used to express RDF content. When used in this way, a
> dataset should be understood to have at least the same content as its default
> graph. Note however that replacing the default graph of a dataset by a
> logically equivalent graph will not in general produce a structurally similar
> dataset, since it may for example disrupt co-occurrences of blank nodes
> between the default graph and other graphs in the dataset, which may be
> important for reasons other than the semantics of the graphs in the dataset.
>
> Other semantic extensions and entailment regimes may place further semantic
> conditions and restrictions on RDF datasets, just as with RDF graphs. One
> such extension, for example, could set up a modal-like interpretation
> structure so that entailment between datasets would require RDF graph
> entailments between the graphs with the same name (adding in empty graphs as
> required).
>
> ]]
>
>
> (I didn't really understand the last two sentences and just left them
> unchanged and crossed my fingers)
The idea is to allow extensions which DO impose this naming condition. So we
could for example say that using some new vocabulary item in a dataset (say,
including < > rdf:type rdf:Referential . in the default graph) imposes this
names-shall-refer-to-named-graphs conditon on the named graphs in the dataset,
and this is a semantic extension to RDF. This would deflect the opposition to
your SHOULD from people who want to use a different convention.
Pat
>
> And then any changes to concepts would be merely editorial.
>
> Jeremy
>
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