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Re: Issue-89, proposal 3: Duplication of triples & inferencing

From: Henry Story <henry.story@bblfish.net>
Date: Thu, 12 Dec 2013 20:01:01 +0100
Cc: Linked Data Platform WG <public-ldp-wg@w3.org>
Message-Id: <0DFD12DF-83A9-4737-A665-6A0C997048D6@bblfish.net>
To: Arnaud LeHors <lehors@us.ibm.com>

On 12 Dec 2013, at 19:20, Arnaud Le Hors <lehors@us.ibm.com> wrote:

> While true, it's been pointed out before, several times, that this would fall short of addressing the use case at hand: allowing one to define a container over existing data by leveraging a domain specific vocabulary. 

I am not sure I understand. The use case is I suppose that one should
be able to publish existing data using LDP. It can't be a requirement
to publish the data in an LDPC in particular. 

It seems obvious that one can publish any data in an LDPR ( that is not
an LDPC of course ). So the use case is satisfied anyway.

Can anyone explain in particular why the data MUST be placed in an 
LDPC?

> It's this new relationship that should be inferred.
> --
> Arnaud  Le Hors - Software Standards Architect - IBM Software Group
> 
> 
> Henry Story <henry.story@bblfish.net> wrote on 12/12/2013 09:27:28 AM:
> 
> > From: Henry Story <henry.story@bblfish.net> 
> > To: Linked Data Platform WG <public-ldp-wg@w3.org>, 
> > Date: 12/12/2013 09:31 AM 
> > Subject: Issue-89, proposal 3: Duplication of triples & inferencing 
> > 
> > Part 3 of Issue-89 creates a relation ldp:propertiesOnlyResource
> > to allow an LDPC to point in its header to the "membership properties".
> > The reason for this is to avoid so called duplication of triples.
> > 
> > The duplication of triples is an issue mostly for the 
> > ldp:DirectContainer as is visible for a container such
> > as the following
> > 
> > <> a ldp:DirectContainer;
> >         ldp:containerResource <>;
> >         ldp:containsRelation m:manages;
> >     ldp:xyz <doc1>, <doc2>, <doc3> ;
> >     m:manages <doc1>, <doc2>, <doc3> .
> > 
> > ( I am using ldp:xyz for what alexander in ISSUE-89 calls 
> >   ldp:contains. You can replace it without loss here and 
> >   throughout this e-mail. )
> > 
> > But according to the rule such as the one used in the Membership wiki [1]
> > it would be very easy to determine the "membership triples" using only 
> > the ldp:xyz relations
> > 
> > PREFIX ldp: <http://www.w3.org/ns/ldp#>
> > 
> > CONSTRUCT { ?subject ?predicate ?object }
> > WHERE {
> >    ?ldpc a ldp:DirectContainer;
> >         ldp:containerResource ?subject;
> >         ldp:containsRelation ?predicate;
> > 
> >    ?ldpc ldp:xyz ?document .
> >    BIND (?document AS ?object)                             # the 
> > POSTed resource is the member
> >  } UNION {
> >    ?ldpc a ldp:DirectContainer;
> >         ldp:containerResource ?object;
> >         ldp:containedByRelation ?predicate.                   # 
> > ldp:containedByRelation is used
> >    
> >    ?ldpc ldp:xyz ?document .
> >    BIND (?document AS ?object)
> >  }
> > }
> > 
> > In that case duplication is not a problem at all,
> > since a client could just infer the "membership triples"
> > from the ldp:xyz ones using that query.
> > 
> > On the other hand if such a rule is not true, and cannot
> > be written out, then there is no duplication, since the
> > "membership triples" are in fact different triples, and
> > have no necessary relation to the ldp:xyz ones.
> > 
> > But then this does give one a good reason for having them in a
> > different possibly server managed resource. 
> > 
> > 
> > 
> > 
> > [1]in the Membership wiki "Determining the membership  triples to be
> > added when a new member 
> > is created"  http://www.w3.org/2012/ldp/wiki/
> > Membership#Determining_the_membership_triples_to_be_added_when_a_new_member_is_created
> > 
> > 
> > Social Web Architect
> > http://bblfish.net/
> > 
> > 

Social Web Architect
http://bblfish.net/
Received on Thursday, 12 December 2013 19:01:36 UTC

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