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Re: Union operations on graphs

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Sat, 24 Sep 2016 15:10:07 -0700
To: Dimitris Kontokostas <kontokostas@informatik.uni-leipzig.de>, Holger Knublauch <holger@topquadrant.com>
Cc: "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>
Message-ID: <a50767cc-e264-2cef-f558-fb7ccd967aa7@gmail.com>
This is getting better.

However, it still appears possible that running a SHACL processor in an RDF
store could change the proto-shape graph or the proto-data graph.   I expected
wording something like:

SHACL processors MUST NOT change the graphs that they use to construct the
shapes graph or the data graph, even if these graphs are part of an RDF store
that allows changes to its stored graphs.  SHACL processors MAY store the
graphs that they create, such as a graph containing validation results, and
this operation MAY change existing graphs in an RDF store, but not any of the
graphs that were used to construct the shapes graph or the data graph.  SHACL
processing is thus idempotent.


On 09/24/2016 06:53 AM, Dimitris Kontokostas wrote:
> Hi Peter and thank you for your feedback
> I tried to work further on this here
> <https://github.com/w3c/data-shapes/commit/339b655f82463161b954684ea205b3c67fb483e8>,
> let me know if this resolves the issue.
> Thanks,
> Dimitris
> On Friday, September 23, 2016, Holger Knublauch <holger@topquadrant.com
> <mailto:holger@topquadrant.com>> wrote:
>     On 23/09/2016 11:36, Peter F. Patel-Schneider wrote:
>             union operations on data graphs and shapes graphs
>             It is unclear just what the data graph and the shapes graph are.
>             There is
>         wording that both of these cannot be changed. However, there is also
>         wording
>         that various kinds of union operations are to be performed on shapes and
>         data graphs.
>                  Comment (HK): The only place I could find "union" was about
>             handling
>         of owl:imports, which states that the result of this union is used as
>         shapes
>         graph. This looks OK to me. Could you clarify what you mean?
>                  Comment (DK): I tried to make the wording clearer here:
>         https://github.com/w3c/data-shapes/commit/b6fd2db5719cc9c9bdec464acdd2aefc8d0b5b68
>         <https://github.com/w3c/data-shapes/commit/b6fd2db5719cc9c9bdec464acdd2aefc8d0b5b68>
>         I don't find this much better.  If the shapes graph and the data graph
>         cannot be changed then there should not be wording about unioning,
>         extending, or otherwise modifying the shapes graph or the data graph.
>     Dimitris, do you have time to revise this further? I guess we need to find
>     a different term than "shapes graph" for the originally supplied graph.
>     The real shapes graph may be the one that is the output of the transitive
>     closure process.
>     Thanks
>     Holger
Received on Saturday, 24 September 2016 22:10:41 UTC

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