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proposed second reply to Jeremy's comment about named graphs

From: Peter Patel-Schneider <pfpschneider@gmail.com>
Date: Wed, 11 Sep 2013 13:28:08 -0700
Message-ID: <CAMpDgVwf-mxrt4=_xTDZLZ-B0S+pUEUkDbk9N8dDrdR4rKft_Q@mail.gmail.com>
To: RDF WG <public-rdf-wg@w3.org>
Dear Jeremy:

This is a second official response to your comment about named graphs in
http://lists.w3.org/Archives/Public/public-rdf-comments/2013Jul/0021.htmland
http://lists.w3.org/Archives/Public/public-rdf-comments/2013Sep/0005.html


The RDF Working Group believes that there are several ways in which RDF
graphs and datasets are and will be used.  These include ways that fit into
your use cases, where the graph names denote the graph they name or some
other formal graph-related construct and where you would indeed say
something like

jjc:graph {
  jjc:graph dc:creator "Jeremy J. Carroll" .
}

However, there are also ways that do not fit into your use cases, for
example where the graph names are IRIs that denote some other entity, such
as

jjc:jjc {
  jjc:jjc rdf:type foaf:Person .
  jjc:jjc foaf:lastName "Carroll" .
  jjc:jjc foaf:knows jjc:pfps .
}

If the RDF semantics required that all graph names denote graph-related
constructs this would interfere with these other use cases.  Therefore the
RDF
Working Group decided to not so require.

Further the RDF Working Group was unable to agree on even a weak theory of
named RDF graphs, such as one conditioned on explicit typing.  Even the
nature of what graph names might denote was problematic: does the name of an
RDF graph denote the graph itself, does it denote some other construct that
is related to the graph, or does it even denote the semantic meaning of the
graph?

Therefore the working group has produced a very minimal specification for
RDF datasets and named graphs that does not depend on denotation.

This approach produces maximally compatability, but does not produce
inferences that might be desirable in some use cases.  If you do want
certain inferences to be part of your approach, such as the first example
above entailing
  jjc:graph rdf:type jjc:Graph.
you can define and implement a particular RDF entailment regime that
sanctions these inferences.

The RDF Working Group believes that this minimal approach will allow
different approaches to named graphs to coexist some allowing what you want
and others incompatible with what you want.  The flourishing approaches can
then be considered for standardization at a later time.
Received on Wednesday, 11 September 2013 20:28:36 UTC

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