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Re: proposed second reply to Jeremy's comment about named graphs

From: Sandro Hawke <sandro@w3.org>
Date: Wed, 11 Sep 2013 22:41:43 -0400
Message-ID: <523129E7.2030704@w3.org>
To: Pat Hayes <phayes@ihmc.us>
CC: Peter Patel-Schneider <pfpschneider@gmail.com>, RDF WG <public-rdf-wg@w3.org>
On 09/11/2013 08:43 PM, Pat Hayes wrote:
> I like this. Is it a good idea to also refer to the notes that Sandro and Pierre-Antoine are supposed to be writing? Just to show we havnt stopped worrying about it, you understand.

There's seems to be some lack of community memory on this.  I already 
gave Jeremy the formal reply to Jeremy's rdf:Graph comment, in which I 
explained about those two notes, etc [1].   He said he still wasn't 
happy [2].    I asked for more details [3], and he gave test cases [4] 
and proposed text [5].   I think we need to respond to *those* not to 
his earlier comments.


I haven't yet had a chance to read and think about [4] and [5].

        -- Sandro

> Pat
> On Sep 11, 2013, at 1:28 PM, Peter Patel-Schneider wrote:
>> 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.html and
>> 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.
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Received on Thursday, 12 September 2013 02:41:51 UTC

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