Re: on values

>From what I understand these are two separate issues .

in Peter's comments, the problem he states is that we do not confine our
value restrictions in shapes graphs / data graphs or in  SHACL related
graphs in general.
Peter, is this the case? We recently added an explanation in the
conformance section that the spec describes the expected structure of the
language.
Isn't this (expected) sufficient to allow other uses of shacl properties /
classes?

Simon's comment has to do with OWL reasoning. Once OWL reasoning is
applied, incorrect syntax could become valid or the other way around.
However, SHACL does not reasoning, it takes the given graph as is

_:morningstar owl:sameAs :Venus.
    _:x sh:targetNode _:morningstar.

:morningstar owl:sameAs _:Venus.
    _:x sh:targetNode :morningstar.




On Mon, Dec 5, 2016 at 4:13 AM, Irene Polikoff <irene@topquadrant.com>
wrote:

> I do not understand the problem.
>
> In Simon's example _:Morningstar and :Venus are two different/separate
> nodes, so I am not sure what this illustrates. The fact that there is a
> owl:sameAs statement between a blank node and an IRI wouldn't change
> anything at the RDF level or SHACL level.
>
> It would help to hear from Peter what specific language makes him think
> the spec is talking about all RDF graphs as opposed to graphs defining
> SHACL shapes.
>
> Sent from my iPhone
>
> On Dec 4, 2016, at 12:49 PM, Solbrig, Harold R., M.S. <
> Solbrig.Harold@mayo.edu> wrote:
>
> https://www.w3.org/TR/shacl-abstract-syntax/
>
> From: Simon Spero <sesuncedu@gmail.com>
> Date: Sunday, December 4, 2016 at 11:09 AM
> To: "public-rdf-shapes@w3.org" <public-rdf-shapes@w3.org>
> Subject: Re: on values
> Resent-From: <public-rdf-shapes@w3.org>
> Resent-Date: Sunday, December 4, 2016 at 11:09 AM
>
> If I undestand the issue correctly, the problem appears to be that :
>
> (1) the SHACL specification needs to impose a *syntactic* constraint on
> the third position in some kinds of RDF triples - specifically that the
> syntactic form MUST NOT be that of an unreified blank node (i.e. "_:x")
>
> but
>
> (2) the specification refers to the *value* of this part of the triple,
> where the syntactic form used to refer to the name is no longer relevant;
> to be unoriginal,
>
>     _:morningstar owl:sameAs :Venus.
>     _:x sh:targetNode _:morningstar.
>
> It may be possible to fix the document by explicitly  distinguishing
> between the syntax and semantics; alternatively it may be less confusing to
> define an abstract syntax for SHACL with a mapping from that syntax into
> RDF.
>
> Simon
>
>
> On Dec 3, 2016 9:51 PM, "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
> wrote:
>
> Certainly it is fine for the SHACL document to state conditions about
> SHACL-related things (SHACL graphs, SHACL shapes, SHACL constraints,
> whatever).  But the current document goes much farther.
>
> Of course, what the document currently says isn't anything that the
> document
> should be saying and almost certainly isn't what is intended.  These parts
> of
> the document thus need to be fixed.
>
> peter
>
>
> On 12/03/2016 05:50 PM, Irene Polikoff wrote:
> > Firstly, I do not know if it is OK or not for this value to be a blank
> node. I’ll leave up to the editors to clarify.
> >
> > Secondly, assuming it is not OK, I believe it to be totally acceptable
> for the SHACL spec to say that for SHACL shapes values of a specific
> property must not be blank nodes. Users creating shapes should not be using
> blank nodes as values for this property.  Such statement does not put any
> requirements or restrictions or assumptions on all RDF graphs. It only
> concerns itself with how shapes must be specified.
> >
> >> On Dec 3, 2016, at 7:57 PM, Peter F. Patel-Schneider <
> pfpschneider@gmail.com> wrote:
> >>
> >> That is indeed what you said.  Prohibiting the value of sh:targetNode
> from
> >> being a blank node says something about all RDF graphs.
> >>
> >> This is what the wording in the SHACL document is stating.
> >>
> >> peter
> >>
> >>
> >> On 12/03/2016 04:45 PM, Irene Polikoff wrote:
> >>> This is not what I said
> >>>
> >>>> On Dec 3, 2016, at 5:46 PM, Peter F. Patel-Schneider <
> pfpschneider@gmail.com> wrote:
> >>>>
> >>>> The SHACL spec can say something about all RDF graphs?  That doesn't
> make sense.
> >>>>
> >>>> peter
> >>>>
> >>>>
> >>>> On 12/03/2016 02:44 PM, Irene Polikoff wrote:
> >>>>> By saying so in the spec.
> >>>>>
> >>>>>> On Dec 3, 2016, at 4:09 PM, Peter F. Patel-Schneider <
> pfpschneider@gmail.com
> >>>>>> <mailto:pfpschneider@gmail.com>> wrote:
> >>>>>>
> >>>>>> But how can the value of sh:targetNode be prohibited from being a
> blank node?
> >>>>>
> >>>
> >
>
>
>


-- 
Dimitris Kontokostas
Department of Computer Science, University of Leipzig & DBpedia Association
Projects: http://dbpedia.org, http://rdfunit.aksw.org,
http://aligned-project.eu
Homepage: http://aksw.org/DimitrisKontokostas
Research Group: AKSW/KILT http://aksw.org/Groups/KILT