- From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
- Date: Thu, 10 Mar 2016 21:16:17 -0800
- To: Holger Knublauch <holger@topquadrant.com>, public-data-shapes-wg@w3.org
There isn't anything that currently says that the object of a sh:property triple can't be a sh:InversePropertyConstraint, i.e., this is a valid shapes graph currently. It thus appears that this example would pass all inspections and then work incorrectly. As you say, making this syntactically illegal will solve this particular problem. I do wonder if there are any other cases like this. I just happened to notice this because of what you said about different code being needed for the different cases. peter On 03/10/2016 08:32 PM, Holger Knublauch wrote: > That would be a modeling error, i.e. an invalid shapes graph. The rules state > what the sh:defaultValueType is for sh:property and sh:inverseProperty. > However, the "range" of sh:property is limited to sh:PropertyConstraint only, > so it cannot have an sh:InversePropertyConstraint as values. If someone > creates such a situation then it would evaluate both. This case can easily be > checked using SHACL constraints at "compile time", reporting an error in the > shapes graph. We could also make sh:PropertyConstraint and > sh:InversePropertyConstraint disjoint... > > Holger > > > On 11/03/2016 14:22, Peter F. Patel-Schneider wrote: >> Oops, I messed up the example. Sorry for the confusion. >> >> Here is what I meant >> >> ex:s a sh:Shape ; >> sh:property _:c ; >> sh:property [ sh:predicate ex:q ; >> sh:valueShape [ sh:inverseProperty _:c ] ] . >> >> _:c [ sh:predicate ex:p ; >> sh:minCount 5 ] . >> >> peter >> >> >> >> On 03/10/2016 08:12 PM, Holger Knublauch wrote: >>> On 11/03/2016 13:38, Peter F. Patel-Schneider wrote: >>>> _:c will be both a sh:PropertyConstraint and sh:InversePropertyConstraint. >>>> Which SPARQL query will it pick? Both? In this case things might work out, >>> Yes both. I am glad we agree. >> We don't agree, even here. Doing both works only because _:c was used in the >> same place. >> >>>> but what happens if the incoming links are from different places, as in >>>> >>>> ex:s a sh:Shape ; >>>> sh:property _:c ; >>>> sh:property [ sh:predicate ex:q ; >>>> sh:valueShape [ sh:property _:c ] ] . >>>> >>>> _:c [ sh:predicate ex:p ; >>>> sh:minCount 5 ] . >>> I see no problem there. In both cases it's a sh:PropertyConstraint based on >>> the sh:defaultValueType of sh:property. They are not executed at the same >>> time, and on different focus nodes. >>> >>> Does this answer your ticket? >>> >>> Holger >>> >>> >>>> peter >>>> >>>> >>>> >>>> On 03/10/2016 04:43 PM, Holger Knublauch wrote: >>>>> In the current draft this is handled by sh:defaultValueType: >>>>> >>>>> ex:s a sh:Shape ; >>>>> sh:property _:c ; >>>>> sh:inverseProperty _:c . >>>>> _:c [ sh:predicate ex:p ; >>>>> sh:minCount 5 ] . >>>>> >>>>> >>>>> The engine will "add" two type triples: >>>>> >>>>> _:c a sh:PropertyConstraint . >>>>> _:c a sh:InversePropertyConstraint . >>>>> >>>>> The engine can then pick the correct validator (SPARQL query) for each >>>>> rdf:type of that constraint. >>>>> >>>>> Holger >>>>> >>>>> >>>>> On 11/03/2016 7:15, RDF Data Shapes Working Group Issue Tracker wrote: >>>>>> shapes-ISSUE-134 (knowing inverse): does SHACL syntax distinguish inverse >>>>>> property constraints [SHACL Spec] >>>>>> >>>>>> http://www.w3.org/2014/data-shapes/track/issues/134 >>>>>> >>>>>> Raised by: Peter Patel-Schneider >>>>>> On product: SHACL Spec >>>>>> >>>>>>> From >>>>>> https://lists.w3.org/Archives/Public/public-data-shapes-wg/2016Mar/0106.html >>>>>> >>>>>> >>>>>> Some constraint types require different SPARQL queries (or JavaScript or >>>>>> whatever) depending on the direction of a property (or even worse, for an >>>>>> arbitrary path). For example sh:minCount needs to count subjects versus >>>>>> objects. >>>>>> >>>>>> Is it possible to determine whether a sh:minCount constraint is an inverse >>>>>> or not? Consider >>>>>> >>>>>> ex:s a sh:Shape ; >>>>>> sh:property _:c ; >>>>>> sh:inverseProperty _:c . >>>>>> _:c [ sh:predicate ex:p ; >>>>>> sh:minCount 5 ] . >>>>>> >>>>>> >>>>>> >>> > >
Received on Friday, 11 March 2016 05:16:49 UTC