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Re: divergence in the definition of sh:minCount

From: Dimitris Kontokostas <kontokostas@informatik.uni-leipzig.de>
Date: Tue, 27 Sep 2016 10:14:42 +0300
Message-ID: <CA+u4+a30N+0V3xgBJUzX_wpH+MgnwNumTF53_dUp5NHOsK4hOg@mail.gmail.com>
To: Irene Polikoff <irene@topquadrant.com>
Cc: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>, "public-rdf-sha." <public-rdf-shapes@w3.org>
This commit should resolve this issue
https://github.com/w3c/data-shapes/commit/7ecd90e51373f8934a6160068e1eb37aa8d214bf

When we introduced property paths we were not sure which is the correct way
to handle duplicates but after your comments, it makes sense to handle them
as sets.

On Tue, Sep 27, 2016 at 7:19 AM, Irene Polikoff <irene@topquadrant.com>
wrote:

> By the wording issue, I meant that what is being counted here are triples,
> not łvalue nodes˛ as the description in the spec says.
>
> When there is a specific property, number of value nodes equals number of
> triples since there is always the same subject and predicate. However,
> with the alternative paths, it is clear that the query is counting triples
> and that this count can be different from the number of values - as the
> example shows.
>
> I think if the definition as described by the words is to remain the same,
> then the query would need to change.
>
> Irene
>
>
>
>
> On 9/26/16, 5:00 PM, "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
> wrote:
>
> >It's not really a language/wording issue, except perhaps if you are Humpty
> >Dumpty.   There are only two value here, no more.  SHACL has always been
> >based
> >on values, not paths.  This is one way in which it differs from shape
> >expressions.
> >
> >peter
> >
> >On 09/26/2016 01:48 PM, Irene Polikoff wrote:
> >> I thought what Peter is saying that even if the count is four, there
> >>are only
> >> two nodes in the graph in this example, so this is a language/wording
> >>issue.
> >>
> >> Irene
> >>
> >>
> >> From: Dimitris Kontokostas <kontokostas@informatik.uni-leipzig.de
> >> <mailto:kontokostas@informatik.uni-leipzig.de>>
> >> Date: Monday, September 26, 2016 at 3:11 PM
> >> To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com
> >> <mailto:pfpschneider@gmail.com>>
> >> Cc: "public-rdf-sha." <public-rdf-shapes@w3.org
> >><mailto:public-rdf-shapes@w3.org>>
> >> Subject: Re: divergence in the definition of sh:minCount
> >> Resent-From: <public-rdf-shapes@w3.org
> >><mailto:public-rdf-shapes@w3.org>>
> >> Resent-Date: Mon, 26 Sep 2016 19:12:00 +0000
> >>
> >> Maybe it is something very obvious but I still cannot see it.
> >>
> >> however, I improved the wording for the property path value nodes. It
> >>was
> >> using subject and object which was not correct, shapes can use also
> >>literals
> >> as focus nodes
> >>
> >>https://github.com/w3c/data-shapes/commit/f1d525b82ce8a74092826e768159db
> 6
> >>01270033a
> >>
> >> On Mon, Sep 26, 2016 at 6:55 PM, Peter F. Patel-Schneider
> >> <pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>> wrote:
> >>
> >>     You mean that you got back 4 results when running the SPARQL query.
> >> That's
> >>     different from "the number of value nodes", which is my point.
> >>
> >>     peter
> >>
> >>
> >>     On 09/26/2016 12:30 AM, Dimitris Kontokostas wrote:
> >>     > Hi Peter,
> >>     >
> >>     > I tried your example and I got 4 "value nodes" back which is in
> >>line with the
> >>     > duplicate value node comment above.
> >>     >
> >>     > I am trying to see the problem here, is it the following wording
> >>from section 4?
> >>     > "For property constraints that have a sh:path the value nodes are
> >>the objects
> >>     > in the data graph that can be reached by following the given
> >>property path
> >>     > starting with the focus node as subject based on the evaluation
> >>rules defined
> >>     > by SPARQL 1.1"
> >>     >
> >>     > I think this can be improved but I cannot see if there is a wrong
> >>definition
> >>     > there.
> >>     >
> >>     > Thanks,
> >>     > Dimitris
> >>     >
> >>     > On Sun, Sep 25, 2016 at 12:43 AM, Peter F. Patel-Schneider
> >>     > <pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>
> >>     <mailto:pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>>>
> >>wrote:
> >>     >
> >>     >     Even if you "count all nodes, even duplicates", there is
> >>still a violation in
> >>     >
> >>     >     Data:
> >>     >       :john :child :bill .
> >>     >       :john :son :bill .
> >>     >       :john :child :mary .
> >>     >       :john :daughter :mary .
> >>     >
> >>     >     Shape
> >>     >       s:s1 rdf:type sh:Shape ;
> >>     >         sh:targetNode :john ;
> >>     >         sh:property [ sh:path [ sh:alternativePath ( :child :son
> >>:daughter ) ] ;
> >>     >                       sh:minCount 3 ] .
> >>     >
> >>     >     If something other than "A validation result must be produced
> >>if the number of
> >>     >     value nodes is less than the value of sh:minCount." is
> >>desired then this
> >>     >     wording can no longer be used, particularly given the wording
> >>about path-based
> >>     >     property constraints at the beginning of Section 4.
> >>     >
> >>     >     peter
> >>     >
> >>     >
> >>     >
> >>     >     On 09/24/2016 07:12 AM, Dimitris Kontokostas wrote:
> >>     >     > Hi Peter,
> >>     >     >
> >>     >     > is this about the fact that property paths might return
> >>duplicate value nodes
> >>     >     > or something else?
> >>     >     > In this case, we count all nodes, even duplicates for
> >>cardinality restrictions
> >>     >     >
> >>     >     > Thanks,
> >>     >     > Dimitris
> >>     >     >
> >>     >     > On Fri, Sep 23, 2016 at 9:17 PM, Peter F. Patel-Schneider
> >>     >     > <pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>
> >>     <mailto:pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>>
> >>     >     <mailto:pfpschneider@gmail.com <mailto:pfpschneider@gmail.com
> >
> >>     <mailto:pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>>>>
> >>wrote:
> >>     >     >
> >>     >     >     The textual and SPARQL definitions of sh:minCount do
> >>not align when
> >>     >     paths
> >>     >     >     are allowed.
> >>     >     >
> >>     >     >
> >>     >     >     A validation result must be produced if the number of
> >>value nodes is
> >>     >     less
> >>     >     >     than the value of sh:minCount.
> >>     >     >
> >>     >     >     SELECT $this
> >>     >     >     WHERE {OPTIONAL {$this $PATH ?value .}}
> >>     >     >     GROUP BY $this
> >>     >     >     HAVING (COUNT(?value) < $minCount)
> >>     >     >
> >>     >     >
> >>     >     >
> >>     >     >     Peter F. Patel-Schneider
> >>     >     >     Nuance Communications
> >>     >     >
> >>     >     >
> >>     >     >
> >>     >     >
> >>     >     > --
> >>     >     > 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
> >><http://aksw.org/DimitrisKontokostas>
> >>     >     <http://aksw.org/DimitrisKontokostas
> >><http://aksw.org/DimitrisKontokostas>>
> >>     >     > Research Group: AKSW/KILT http://aksw.org/Groups/KILT
> >>     >     >
> >>     >
> >>     >
> >>     >
> >>     >
> >>     > --
> >>     > 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
> >><http://aksw.org/DimitrisKontokostas>
> >>     > Research Group: AKSW/KILT http://aksw.org/Groups/KILT
> >>     >
> >>
> >>
> >>
> >>
> >> --
> >> 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
> >>
>
>
>
>
>


-- 
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
Received on Tuesday, 27 September 2016 07:15:43 UTC

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