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Re: More on: Should information be merged from several RDF files?

From: Simon Spero <sesuncedu@gmail.com>
Date: Tue, 8 Jul 2014 00:35:07 -0400
Message-ID: <CADE8KM6=8Y5en=ws102vj4=Kgb+t8xG20=C9kbOA0Z-jT1Shpg@mail.gmail.com>
To: Pat Hayes <phayes@ihmc.us>
Cc: semantic-web@w3.org, Victor Porton <porton@narod.ru>
Dark triples?
http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Mar/0253.html

Simon
On Jul 7, 2014 11:05 PM, "Pat Hayes" <phayes@ihmc.us> wrote:

>
> On Jul 7, 2014, at 4:17 PM, Victor Porton <porton@narod.ru> wrote:
>
> > I am writing a program.
> >
> > I read RDF files while executing my program.
> >
> > After each RDF loaded, my program does some actions (and probably
> terminates).
> >
> > It is not predictable which RDF file will be loaded next, because in
> intervals between loading RDF files my program does some computations and
> the next loaded RDF file depends on these computation.
> >
> > As such, I cannot first load all RDF files and merge information in
> them. Instead of this I need to load RDF files one-by-one and update my
> program data structure after reading each RDF file.
> >
> > If I would read all RDF files at once I would be able just to merge data
> from all RDF files. But I cannot do that.
> >
> > Upon reading each RDF file, I update internal data structures of my
> program based on RDF triples loaded.
>
> So far, nothing you have said tells us why you are using RDF for this
> application. RDF is intended for use in transmitting assertional
> information across the Web, analogously with how HTML is designed to
> transmit hypertext. Does your application have any relationship to this
> kind of use?
>
> > I cannot base building these internal data structures of my program on
> the result of set-theoretic union of all RDF triples loaded till the
> moment. The reason for this is that loading an additional RDF may render my
> data inconsistent
>
> Two points in response.
>
> First, this notion of 'inconsistent' which you are using is not the RDF
> notion of consistency. You are therefore, apparently, using some kind
> semantic extension of RDF. (See
> http://www.w3.org/TR/2014/REC-rdf11-mt-20140225/#semantic-extensions-and-entailment-regimes
> ) You might do well to try to describe this extension more precisely before
> proceeding. (The restriction you describe below is defined in the OWL
> semantic extension: it is the requirement that the predicate be a
> functional property.)
>
> Second, it is of the essence of RDF and RDF extensions that they can
> express inconsistencies. RDF users should be prepared to deal with clashes
> or inconsistencies between data items and have strategies for dealing with
> them. These might range form simply throwing an error, to a sophisticated
> truth-maintenance system which finds maximally consistent subsets of RDF
> triples.
>
> > (if it has two or more different objects for a predicate which should
> have no more than on value, as in an example below). So this would require
> removal of some data from my program data structures, what would aimlessly
> complicate the code. I want only to add new data structures, not remove
> them, to make my program easier.
>
> With respect, this is rather like saying that I want to avoid doing
> arithmetic, so I want all my sums to be correct without having to add them
> up. RDF simply carries data to your code: if that data is faulty or more
> complicated than you would prefer it to be, don't blame RDF or seek to find
> an RDF magic bullet.
>
> > So the only remaining option is to load RDF one-by-one and construct new
> internal data structures of my program based only on the last loaded RDF
> file (not all loaded RDF files together).
>
> You have decided to resolve contradictions by preferring the most-recently
> read data over 'older' data. This sounds like a possibly workable
> simplification, but I would not want to rely on it for anything important.
>
> > A question remains:
> >
> > # file-1.rdf
> > <http://example.com> <#property-which-can-have-only-one-value> 1 .
> >
> > # file-2.rdf
> > <http://example.com> <#property-which-can-have-only-one-value> 2 .
> >
> > Let we load first file-1.rdf and then later file-2.rdf. Should the
> triple from file-2.rdf be ignored? Or should I construct a new data
> structure from the data of both files, as if the subject URLs in these
> files would be different?
>
> All of these are possible strategies for resolving conflicts. Nothing in
> RDF prefers one over the other. The choice is yours. Only someone who knows
> what your data means, and how it is created, would be able to make an
> intelligent decision here. There is no magic bullet.
>
> Pat Hayes
>
> >
> > Here is my project, by the way:
> > http://freesoft.portonvictor.org/namespaces.xml
> >
> > --
> > Victor Porton - http://portonvictor.org
> >
> >
>
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>
>
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Received on Tuesday, 8 July 2014 04:35:35 UTC

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