Re: AW: Constraints on a property in a SKOS hierarchy

On 2021-09-22 10:00 pm, felix@sasakiatcf.com wrote:
>
> Thanks a lot for the example, Holger.
>
> I tried this out. Attached is
>
>  1. your shape testshape.ttl
>  2. a testfile that throws an error, as expected
>     testdata-fails-as-exepected.ttl
>  3. a testfile that does not throw an error: testdata-does-not-fail.ttl .
>
> The difference between 2) and 3) is that 3) has the same value for the 
> ex:myProperty property. Does this make a difference?
>
Ah yes, that's a good point. Path expressions will eliminate duplicates, 
so it will pass the maxCount constraint for this corner case!

If the hierarchy is acyclic, the following should work, doing a 
skos:broader+ instead of skos:broader*. It basically means

"None of the parent concepts can have a value for ex:myProperty".

ex:BranchShape
     a sh:NodeShape ;
     sh:targetSubjectsOf ex:myProperty ;
     sh:property [
         sh:path ( [ sh:oneOrMorePath skos:broader ] ex:myProperty ) ;
         sh:maxCount 0 ;
     ] .

(This is again untested, as a dry pen-and-paper exercise)

Holger


> I am using the TopQuadrant implementation
>
> https://github.com/TopQuadrant/shacl/ 
> <https://github.com/TopQuadrant/shacl/>
>
> Regards
>
> Felix
>
> *Von:*Holger Knublauch <holger@topquadrant.com>
> *Gesendet:* Mittwoch, 22. September 2021 02:14
> *An:* public-shacl@w3.org
> *Betreff:* Re: Constraints on a property in a SKOS hierarchy
>
> On 2021-09-21 6:57 pm, felix@sasakiatcf.com 
> <mailto:felix@sasakiatcf.com> wrote:
>
>     Dear all,
>
>     I would like to to the following:
>
>      1. Define a property “ex:myProperty” for a skos:Concept.
>      2. In a given SKOS taxonomy, the following constraint should be
>         formulated: for the taxonomy, the property should appear zero
>         or more times in one “branch” of the taxonomy.
>
> If you really mean zero or more times, then this wouldn't constrain 
> anything. My understanding is you want to say zero or one time, i.e. 
> that there can be at most one value per branch?
>
>     3.
>
>     The following would be a valid SKOS RDF graph:
>
>     example:animal a skos:Concept; ex:myProperty “some value”.
>
>     example:bird a skos:Concept; skos:broader example:animal.
>
>     The following would be a non-valid SKOS RDF graph, since
>     example:bird is connected to another concept (example:animal) that
>     already has ex:myProperty:
>
>     example:animal a skos:Concept; ex:myProperty “some value”.
>
>     example:bird a skos:Concept; skos:broader example:animal;
>     ex:myProperty “some value”.
>
> Given the above assumption, could this simply become a maxCount 1 on a 
> path expression skos:broader* / ex:myProperty?
>
> Untested draft:
>
> ex:BranchShape
>     a sh:NodeShape ;
>     sh:targetSubjectsOf ex:myProperty ;
>     sh:property [
>         sh:path ( [ sh:zeroOrMorePath skos:broader ] ex:myProperty ) ;
>         sh:maxCount 1 ;
>     ] .
>
> I guess instead of the sh:targetSubjectsOf you could also simply 
> attach this to all skos:Concepts.
>
> Holger
>
>     How would I formulate 2) in SHACL?
>
>     Regards
>
>     Felix
>